/src/git/attr.c

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/*
 * Handle git attributes.  See gitattributes(5) for a description of
 * the file syntax, and attr.h for a description of the API.
 *
 * One basic design decision here is that we are not going to support
 * an insanely large number of attributes.
 */

#define USE_THE_REPOSITORY_VARIABLE

#include "git-compat-util.h"
#include "config.h"
#include "environment.h"
#include "exec-cmd.h"
#include "attr.h"
#include "dir.h"
#include "gettext.h"
#include "path.h"
#include "utf8.h"
#include "quote.h"
#include "read-cache-ll.h"
#include "refs.h"
#include "revision.h"
#include "object-store-ll.h"
#include "setup.h"
#include "thread-utils.h"
#include "tree-walk.h"
#include "object-name.h"

char *git_attr_tree;

const char git_attr__true[] = "(builtin)true";
const char git_attr__false[] = "\0(builtin)false";
static const char git_attr__unknown[] = "(builtin)unknown";
#define ATTR__TRUE git_attr__true
#define ATTR__FALSE git_attr__false
#define ATTR__UNSET NULL
#define ATTR__UNKNOWN git_attr__unknown

struct git_attr {
  unsigned int attr_nr; /* unique attribute number */
  char name[FLEX_ARRAY]; /* attribute name */
};

const char *git_attr_name(const struct git_attr *attr)
{
  return attr->name;
}

struct attr_hashmap {
  struct hashmap map;
  pthread_mutex_t mutex;
};

static inline void hashmap_lock(struct attr_hashmap *map)
{
  pthread_mutex_lock(&map->mutex);
}

static inline void hashmap_unlock(struct attr_hashmap *map)
{
  pthread_mutex_unlock(&map->mutex);
}

/* The container for objects stored in "struct attr_hashmap" */
struct attr_hash_entry {
  struct hashmap_entry ent;
  const char *key; /* the key; memory should be owned by value */
  size_t keylen; /* length of the key */
  void *value; /* the stored value */
};

/* attr_hashmap comparison function */
static int attr_hash_entry_cmp(const void *cmp_data UNUSED,
             const struct hashmap_entry *eptr,
             const struct hashmap_entry *entry_or_key,
             const void *keydata UNUSED)
{
  const struct attr_hash_entry *a, *b;

  a = container_of(eptr, const struct attr_hash_entry, ent);
  b = container_of(entry_or_key, const struct attr_hash_entry, ent);
  return (a->keylen != b->keylen) || strncmp(a->key, b->key, a->keylen);
}

/*
 * The global dictionary of all interned attributes.  This
 * is a singleton object which is shared between threads.
 * Access to this dictionary must be surrounded with a mutex.
 */
static struct attr_hashmap g_attr_hashmap = {
  .map = HASHMAP_INIT(attr_hash_entry_cmp, NULL),
};

/*
 * Retrieve the 'value' stored in a hashmap given the provided 'key'.
 * If there is no matching entry, return NULL.
 */
static void *attr_hashmap_get(struct attr_hashmap *map,
            const char *key, size_t keylen)
{
  struct attr_hash_entry k;
  struct attr_hash_entry *e;

  hashmap_entry_init(&k.ent, memhash(key, keylen));
  k.key = key;
  k.keylen = keylen;
  e = hashmap_get_entry(&map->map, &k, ent, NULL);

  return e ? e->value : NULL;
}

/* Add 'value' to a hashmap based on the provided 'key'. */
static void attr_hashmap_add(struct attr_hashmap *map,
           const char *key, size_t keylen,
           void *value)
{
  struct attr_hash_entry *e;

  e = xmalloc(sizeof(struct attr_hash_entry));
  hashmap_entry_init(&e->ent, memhash(key, keylen));
  e->key = key;
  e->keylen = keylen;
  e->value = value;

  hashmap_add(&map->map, &e->ent);
}

struct all_attrs_item {
  const struct git_attr *attr;
  const char *value;
  /*
   * If 'macro' is non-NULL, indicates that 'attr' is a macro based on
   * the current attribute stack and contains a pointer to the match_attr
   * definition of the macro
   */
  const struct match_attr *macro;
};

/*
 * Reallocate and reinitialize the array of all attributes (which is used in
 * the attribute collection process) in 'check' based on the global dictionary
 * of attributes.
 */
static void all_attrs_init(struct attr_hashmap *map, struct attr_check *check)
{
  int i;
  unsigned int size;

  hashmap_lock(map);

  size = hashmap_get_size(&map->map);
  if (size < check->all_attrs_nr)
    BUG("interned attributes shouldn't be deleted");

  /*
   * If the number of attributes in the global dictionary has increased
   * (or this attr_check instance doesn't have an initialized all_attrs
   * field), reallocate the provided attr_check instance's all_attrs
   * field and fill each entry with its corresponding git_attr.
   */
  if (size != check->all_attrs_nr) {
    struct attr_hash_entry *e;
    struct hashmap_iter iter;

    REALLOC_ARRAY(check->all_attrs, size);
    check->all_attrs_nr = size;

    hashmap_for_each_entry(&map->map, &iter, e,
          ent /* member name */) {
      const struct git_attr *a = e->value;
      check->all_attrs[a->attr_nr].attr = a;
    }
  }

  hashmap_unlock(map);

  /*
   * Re-initialize every entry in check->all_attrs.
   * This re-initialization can live outside of the locked region since
   * the attribute dictionary is no longer being accessed.
   */
  for (i = 0; i < check->all_attrs_nr; i++) {
    check->all_attrs[i].value = ATTR__UNKNOWN;
    check->all_attrs[i].macro = NULL;
  }
}

/*
 * Atribute name cannot begin with "builtin_" which
 * is a reserved namespace for built in attributes values.
 */
static int attr_name_reserved(const char *name)
{
  return starts_with(name, "builtin_");
}

static int attr_name_valid(const char *name, size_t namelen)
{
  /*
   * Attribute name cannot begin with '-' and must consist of
   * characters from [-A-Za-z0-9_.].
   */
  if (namelen <= 0 || *name == '-')
    return 0;
  while (namelen--) {
    char ch = *name++;
    if (! (ch == '-' || ch == '.' || ch == '_' ||
           ('0' <= ch && ch <= '9') ||
           ('a' <= ch && ch <= 'z') ||
           ('A' <= ch && ch <= 'Z')) )
      return 0;
  }
  return 1;
}

static void report_invalid_attr(const char *name, size_t len,
        const char *src, int lineno)
{
  struct strbuf err = STRBUF_INIT;
  strbuf_addf(&err, _("%.*s is not a valid attribute name"),
        (int) len, name);
  fprintf(stderr, "%s: %s:%d\n", err.buf, src, lineno);
  strbuf_release(&err);
}

/*
 * Given a 'name', lookup and return the corresponding attribute in the global
 * dictionary.  If no entry is found, create a new attribute and store it in
 * the dictionary.
 */
static const struct git_attr *git_attr_internal(const char *name, size_t namelen)
{
  struct git_attr *a;

  if (!attr_name_valid(name, namelen))
    return NULL;

  hashmap_lock(&g_attr_hashmap);

  a = attr_hashmap_get(&g_attr_hashmap, name, namelen);

  if (!a) {
    FLEX_ALLOC_MEM(a, name, name, namelen);
    a->attr_nr = hashmap_get_size(&g_attr_hashmap.map);

    attr_hashmap_add(&g_attr_hashmap, a->name, namelen, a);
    if (a->attr_nr != hashmap_get_size(&g_attr_hashmap.map) - 1)
      die(_("unable to add additional attribute"));
  }

  hashmap_unlock(&g_attr_hashmap);

  return a;
}

const struct git_attr *git_attr(const char *name)
{
  return git_attr_internal(name, strlen(name));
}

/* What does a matched pattern decide? */
struct attr_state {
  const struct git_attr *attr;
  const char *setto;
};

struct pattern {
  const char *pattern;
  int patternlen;
  int nowildcardlen;
  unsigned flags;   /* PATTERN_FLAG_* */
};

/*
 * One rule, as from a .gitattributes file.
 *
 * If is_macro is true, then u.attr is a pointer to the git_attr being
 * defined.
 *
 * If is_macro is false, then u.pat is the filename pattern to which the
 * rule applies.
 *
 * In either case, num_attr is the number of attributes affected by
 * this rule, and state is an array listing them.  The attributes are
 * listed as they appear in the file (macros unexpanded).
 */
struct match_attr {
  union {
    struct pattern pat;
    const struct git_attr *attr;
  } u;
  char is_macro;
  size_t num_attr;
  struct attr_state state[FLEX_ARRAY];
};

static const char blank[] = " \t\r\n";

/* Flags usable in read_attr() and parse_attr_line() family of functions. */
#define READ_ATTR_MACRO_OK (1<<0)
#define READ_ATTR_NOFOLLOW (1<<1)

/*
 * Parse a whitespace-delimited attribute state (i.e., "attr",
 * "-attr", "!attr", or "attr=value") from the string starting at src.
 * If e is not NULL, write the results to *e.  Return a pointer to the
 * remainder of the string (with leading whitespace removed), or NULL
 * if there was an error.
 */
static const char *parse_attr(const char *src, int lineno, const char *cp,
            struct attr_state *e)
{
  const char *ep, *equals;
  size_t len;

  ep = cp + strcspn(cp, blank);
  equals = strchr(cp, '=');
  if (equals && ep < equals)
    equals = NULL;
  if (equals)
    len = equals - cp;
  else
    len = ep - cp;
  if (!e) {
    if (*cp == '-' || *cp == '!') {
      cp++;
      len--;
    }
    if (!attr_name_valid(cp, len) || attr_name_reserved(cp)) {
      report_invalid_attr(cp, len, src, lineno);
      return NULL;
    }
  } else {
    /*
     * As this function is always called twice, once with
     * e == NULL in the first pass and then e != NULL in
     * the second pass, no need for attr_name_valid()
     * check here.
     */
    if (*cp == '-' || *cp == '!') {
      e->setto = (*cp == '-') ? ATTR__FALSE : ATTR__UNSET;
      cp++;
      len--;
    }
    else if (!equals)
      e->setto = ATTR__TRUE;
    else {
      e->setto = xmemdupz(equals + 1, ep - equals - 1);
    }
    e->attr = git_attr_internal(cp, len);
  }
  return ep + strspn(ep, blank);
}

struct match_attr *parse_attr_line(const char *line, const char *src,
            int lineno, unsigned flags)
{
  size_t namelen, num_attr, i;
  const char *cp, *name, *states;
  struct match_attr *res = NULL;
  int is_macro;
  struct strbuf pattern = STRBUF_INIT;

  cp = line + strspn(line, blank);
  if (!*cp || *cp == '#')
    return NULL;
  name = cp;

  if (strlen(line) >= ATTR_MAX_LINE_LENGTH) {
    warning(_("ignoring overly long attributes line %d"), lineno);
    return NULL;
  }

  if (*cp == '"' && !unquote_c_style(&pattern, name, &states)) {
    name = pattern.buf;
    namelen = pattern.len;
  } else {
    namelen = strcspn(name, blank);
    states = name + namelen;
  }

  if (strlen(ATTRIBUTE_MACRO_PREFIX) < namelen &&
      starts_with(name, ATTRIBUTE_MACRO_PREFIX)) {
    if (!(flags & READ_ATTR_MACRO_OK)) {
      fprintf_ln(stderr, _("%s not allowed: %s:%d"),
           name, src, lineno);
      goto fail_return;
    }
    is_macro = 1;
    name += strlen(ATTRIBUTE_MACRO_PREFIX);
    name += strspn(name, blank);
    namelen = strcspn(name, blank);
    if (!attr_name_valid(name, namelen) || attr_name_reserved(name)) {
      report_invalid_attr(name, namelen, src, lineno);
      goto fail_return;
    }
  }
  else
    is_macro = 0;

  states += strspn(states, blank);

  /* First pass to count the attr_states */
  for (cp = states, num_attr = 0; *cp; num_attr++) {
    cp = parse_attr(src, lineno, cp, NULL);
    if (!cp)
      goto fail_return;
  }

  res = xcalloc(1, st_add3(sizeof(*res),
         st_mult(sizeof(struct attr_state), num_attr),
         is_macro ? 0 : namelen + 1));
  if (is_macro) {
    res->u.attr = git_attr_internal(name, namelen);
  } else {
    char *p = (char *)&(res->state[num_attr]);
    memcpy(p, name, namelen);
    res->u.pat.pattern = p;
    parse_path_pattern(&res->u.pat.pattern,
              &res->u.pat.patternlen,
              &res->u.pat.flags,
              &res->u.pat.nowildcardlen);
    if (res->u.pat.flags & PATTERN_FLAG_NEGATIVE) {
      warning(_("Negative patterns are ignored in git attributes\n"
          "Use '\\!' for literal leading exclamation."));
      goto fail_return;
    }
  }
  res->is_macro = is_macro;
  res->num_attr = num_attr;

  /* Second pass to fill the attr_states */
  for (cp = states, i = 0; *cp; i++) {
    cp = parse_attr(src, lineno, cp, &(res->state[i]));
  }

  strbuf_release(&pattern);
  return res;

fail_return:
  strbuf_release(&pattern);
  free(res);
  return NULL;
}

/*
 * Like info/exclude and .gitignore, the attribute information can
 * come from many places.
 *
 * (1) .gitattributes file of the same directory;
 * (2) .gitattributes file of the parent directory if (1) does not have
 *      any match; this goes recursively upwards, just like .gitignore.
 * (3) $GIT_DIR/info/attributes, which overrides both of the above.
 *
 * In the same file, later entries override the earlier match, so in the
 * global list, we would have entries from info/attributes the earliest
 * (reading the file from top to bottom), .gitattributes of the root
 * directory (again, reading the file from top to bottom) down to the
 * current directory, and then scan the list backwards to find the first match.
 * This is exactly the same as what is_excluded() does in dir.c to deal with
 * .gitignore file and info/excludes file as a fallback.
 */

struct attr_stack {
  struct attr_stack *prev;
  char *origin;
  size_t originlen;
  unsigned num_matches;
  unsigned alloc;
  struct match_attr **attrs;
};

static void attr_stack_free(struct attr_stack *e)
{
  unsigned i;
  free(e->origin);
  for (i = 0; i < e->num_matches; i++) {
    struct match_attr *a = e->attrs[i];
    size_t j;

    for (j = 0; j < a->num_attr; j++) {
      const char *setto = a->state[j].setto;
      if (setto == ATTR__TRUE ||
          setto == ATTR__FALSE ||
          setto == ATTR__UNSET ||
          setto == ATTR__UNKNOWN)
        ;
      else
        free((char *) setto);
    }
    free(a);
  }
  free(e->attrs);
  free(e);
}

static void drop_attr_stack(struct attr_stack **stack)
{
  while (*stack) {
    struct attr_stack *elem = *stack;
    *stack = elem->prev;
    attr_stack_free(elem);
  }
}

/* List of all attr_check structs; access should be surrounded by mutex */
static struct check_vector {
  size_t nr;
  size_t alloc;
  struct attr_check **checks;
  pthread_mutex_t mutex;
} check_vector;

static inline void vector_lock(void)
{
  pthread_mutex_lock(&check_vector.mutex);
}

static inline void vector_unlock(void)
{
  pthread_mutex_unlock(&check_vector.mutex);
}

static void check_vector_add(struct attr_check *c)
{
  vector_lock();

  ALLOC_GROW(check_vector.checks,
       check_vector.nr + 1,
       check_vector.alloc);
  check_vector.checks[check_vector.nr++] = c;

  vector_unlock();
}

static void check_vector_remove(struct attr_check *check)
{
  int i;

  vector_lock();

  /* Find entry */
  for (i = 0; i < check_vector.nr; i++)
    if (check_vector.checks[i] == check)
      break;

  if (i >= check_vector.nr)
    BUG("no entry found");

  /* shift entries over */
  for (; i < check_vector.nr - 1; i++)
    check_vector.checks[i] = check_vector.checks[i + 1];

  check_vector.nr--;

  vector_unlock();
}

/* Iterate through all attr_check instances and drop their stacks */
static void drop_all_attr_stacks(void)
{
  int i;

  vector_lock();

  for (i = 0; i < check_vector.nr; i++) {
    drop_attr_stack(&check_vector.checks[i]->stack);
  }

  vector_unlock();
}

struct attr_check *attr_check_alloc(void)
{
  struct attr_check *c = xcalloc(1, sizeof(struct attr_check));

  /* save pointer to the check struct */
  check_vector_add(c);

  return c;
}

struct attr_check *attr_check_initl(const char *one, ...)
{
  struct attr_check *check;
  int cnt;
  va_list params;
  const char *param;

  va_start(params, one);
  for (cnt = 1; (param = va_arg(params, const char *)) != NULL; cnt++)
    ;
  va_end(params);

  check = attr_check_alloc();
  check->nr = cnt;
  check->alloc = cnt;
  CALLOC_ARRAY(check->items, cnt);

  check->items[0].attr = git_attr(one);
  va_start(params, one);
  for (cnt = 1; cnt < check->nr; cnt++) {
    const struct git_attr *attr;
    param = va_arg(params, const char *);
    if (!param)
      BUG("counted %d != ended at %d",
          check->nr, cnt);
    attr = git_attr(param);
    if (!attr)
      BUG("%s: not a valid attribute name", param);
    check->items[cnt].attr = attr;
  }
  va_end(params);
  return check;
}

struct attr_check *attr_check_dup(const struct attr_check *check)
{
  struct attr_check *ret;

  if (!check)
    return NULL;

  ret = attr_check_alloc();

  ret->nr = check->nr;
  ret->alloc = check->alloc;
  DUP_ARRAY(ret->items, check->items, ret->nr);

  return ret;
}

struct attr_check_item *attr_check_append(struct attr_check *check,
            const struct git_attr *attr)
{
  struct attr_check_item *item;

  ALLOC_GROW(check->items, check->nr + 1, check->alloc);
  item = &check->items[check->nr++];
  item->attr = attr;
  return item;
}

void attr_check_reset(struct attr_check *check)
{
  check->nr = 0;
}

void attr_check_clear(struct attr_check *check)
{
  FREE_AND_NULL(check->items);
  check->alloc = 0;
  check->nr = 0;

  FREE_AND_NULL(check->all_attrs);
  check->all_attrs_nr = 0;

  drop_attr_stack(&check->stack);
}

void attr_check_free(struct attr_check *check)
{
  if (check) {
    /* Remove check from the check vector */
    check_vector_remove(check);

    attr_check_clear(check);
    free(check);
  }
}

static const char *builtin_attr[] = {
  "[attr]binary -diff -merge -text",
  NULL,
};

static void handle_attr_line(struct attr_stack *res,
           const char *line,
           const char *src,
           int lineno,
           unsigned flags)
{
  struct match_attr *a;

  a = parse_attr_line(line, src, lineno, flags);
  if (!a)
    return;
  ALLOC_GROW_BY(res->attrs, res->num_matches, 1, res->alloc);
  res->attrs[res->num_matches - 1] = a;
}

static struct attr_stack *read_attr_from_array(const char **list)
{
  struct attr_stack *res;
  const char *line;
  int lineno = 0;

  CALLOC_ARRAY(res, 1);
  while ((line = *(list++)) != NULL)
    handle_attr_line(res, line, "[builtin]", ++lineno,
         READ_ATTR_MACRO_OK);
  return res;
}

/*
 * Callers into the attribute system assume there is a single, system-wide
 * global state where attributes are read from and when the state is flipped by
 * calling git_attr_set_direction(), the stack frames that have been
 * constructed need to be discarded so that subsequent calls into the
 * attribute system will lazily read from the right place.  Since changing
 * direction causes a global paradigm shift, it should not ever be called while
 * another thread could potentially be calling into the attribute system.
 */
static enum git_attr_direction direction;

void git_attr_set_direction(enum git_attr_direction new_direction)
{
  if (is_bare_repository() && new_direction != GIT_ATTR_INDEX)
    BUG("non-INDEX attr direction in a bare repo");

  if (new_direction != direction)
    drop_all_attr_stacks();

  direction = new_direction;
}

static struct attr_stack *read_attr_from_file(const char *path, unsigned flags)
{
  struct strbuf buf = STRBUF_INIT;
  int fd;
  FILE *fp;
  struct attr_stack *res;
  int lineno = 0;
  struct stat st;

  if (flags & READ_ATTR_NOFOLLOW)
    fd = open_nofollow(path, O_RDONLY);
  else
    fd = open(path, O_RDONLY);

  if (fd < 0) {
    warn_on_fopen_errors(path);
    return NULL;
  }
  fp = xfdopen(fd, "r");
  if (fstat(fd, &st)) {
    warning_errno(_("cannot fstat gitattributes file '%s'"), path);
    fclose(fp);
    return NULL;
  }
  if (st.st_size >= ATTR_MAX_FILE_SIZE) {
    warning(_("ignoring overly large gitattributes file '%s'"), path);
    fclose(fp);
    return NULL;
  }

  CALLOC_ARRAY(res, 1);
  while (strbuf_getline(&buf, fp) != EOF) {
    if (!lineno && starts_with(buf.buf, utf8_bom))
      strbuf_remove(&buf, 0, strlen(utf8_bom));
    handle_attr_line(res, buf.buf, path, ++lineno, flags);
  }

  fclose(fp);
  strbuf_release(&buf);
  return res;
}

static struct attr_stack *read_attr_from_buf(char *buf, size_t length,
               const char *path, unsigned flags)
{
  struct attr_stack *res;
  char *sp;
  int lineno = 0;

  if (!buf)
    return NULL;
  if (length >= ATTR_MAX_FILE_SIZE) {
    warning(_("ignoring overly large gitattributes blob '%s'"), path);
    free(buf);
    return NULL;
  }

  CALLOC_ARRAY(res, 1);
  for (sp = buf; *sp;) {
    char *ep;
    int more;

    ep = strchrnul(sp, '\n');
    more = (*ep == '\n');
    *ep = '\0';
    handle_attr_line(res, sp, path, ++lineno, flags);
    sp = ep + more;
  }
  free(buf);

  return res;
}

static struct attr_stack *read_attr_from_blob(struct index_state *istate,
                const struct object_id *tree_oid,
                const char *path, unsigned flags)
{
  struct object_id oid;
  unsigned long sz;
  enum object_type type;
  void *buf;
  unsigned short mode;

  if (!tree_oid)
    return NULL;

  if (get_tree_entry(istate->repo, tree_oid, path, &oid, &mode))
    return NULL;

  buf = repo_read_object_file(istate->repo, &oid, &type, &sz);
  if (!buf || type != OBJ_BLOB) {
    free(buf);
    return NULL;
  }

  return read_attr_from_buf(buf, sz, path, flags);
}

static struct attr_stack *read_attr_from_index(struct index_state *istate,
                 const char *path, unsigned flags)
{
  struct attr_stack *stack = NULL;
  char *buf;
  unsigned long size;
  int sparse_dir_pos = -1;

  if (!istate)
    return NULL;

  /*
   * When handling sparse-checkouts, .gitattributes files
   * may reside within a sparse directory. We distinguish
   * whether a path exists directly in the index or not by
   * evaluating if 'pos' is negative.
   * If 'pos' is negative, the path is not directly present
   * in the index and is likely within a sparse directory.
   * For paths not in the index, The absolute value of 'pos'
   * minus 1 gives us the position where the path would be
   * inserted in lexicographic order within the index.
   * We then subtract another 1 from this value
   * (sparse_dir_pos = -pos - 2) to find the position of the
   * last index entry which is lexicographically smaller than
   * the path. This would be the sparse directory containing
   * the path. By identifying the sparse directory containing
   * the path, we can correctly read the attributes specified
   * in the .gitattributes file from the tree object of the
   * sparse directory.
   */
  if (!path_in_cone_mode_sparse_checkout(path, istate)) {
    int pos = index_name_pos_sparse(istate, path, strlen(path));

    if (pos < 0)
      sparse_dir_pos = -pos - 2;
  }

  if (sparse_dir_pos >= 0 &&
      S_ISSPARSEDIR(istate->cache[sparse_dir_pos]->ce_mode) &&
      !strncmp(istate->cache[sparse_dir_pos]->name, path, ce_namelen(istate->cache[sparse_dir_pos]))) {
    const char *relative_path = path + ce_namelen(istate->cache[sparse_dir_pos]);
    stack = read_attr_from_blob(istate, &istate->cache[sparse_dir_pos]->oid, relative_path, flags);
  } else {
    buf = read_blob_data_from_index(istate, path, &size);
    if (buf)
      stack = read_attr_from_buf(buf, size, path, flags);
  }
  return stack;
}

static struct attr_stack *read_attr(struct index_state *istate,
            const struct object_id *tree_oid,
            const char *path, unsigned flags)
{
  struct attr_stack *res = NULL;

  if (direction == GIT_ATTR_INDEX) {
    res = read_attr_from_index(istate, path, flags);
  } else if (tree_oid) {
    res = read_attr_from_blob(istate, tree_oid, path, flags);
  } else if (!is_bare_repository()) {
    if (direction == GIT_ATTR_CHECKOUT) {
      res = read_attr_from_index(istate, path, flags);
      if (!res)
        res = read_attr_from_file(path, flags);
    } else if (direction == GIT_ATTR_CHECKIN) {
      res = read_attr_from_file(path, flags);
      if (!res)
        /*
         * There is no checked out .gitattributes file
         * there, but we might have it in the index.
         * We allow operation in a sparsely checked out
         * work tree, so read from it.
         */
        res = read_attr_from_index(istate, path, flags);
    }
  }

  if (!res)
    CALLOC_ARRAY(res, 1);
  return res;
}

const char *git_attr_system_file(void)
{
  static const char *system_wide;
  if (!system_wide)
    system_wide = system_path(ETC_GITATTRIBUTES);
  return system_wide;
}

const char *git_attr_global_file(void)
{
  if (!git_attributes_file)
    git_attributes_file = xdg_config_home("attributes");

  return git_attributes_file;
}

int git_attr_system_is_enabled(void)
{
  return !git_env_bool("GIT_ATTR_NOSYSTEM", 0);
}

static GIT_PATH_FUNC(git_path_info_attributes, INFOATTRIBUTES_FILE)

static void push_stack(struct attr_stack **attr_stack_p,
           struct attr_stack *elem, char *origin, size_t originlen)
{
  if (elem) {
    elem->origin = origin;
    if (origin)
      elem->originlen = originlen;
    elem->prev = *attr_stack_p;
    *attr_stack_p = elem;
  }
}

static void bootstrap_attr_stack(struct index_state *istate,
         const struct object_id *tree_oid,
         struct attr_stack **stack)
{
  struct attr_stack *e;
  unsigned flags = READ_ATTR_MACRO_OK;

  if (*stack)
    return;

  /* builtin frame */
  e = read_attr_from_array(builtin_attr);
  push_stack(stack, e, NULL, 0);

  /* system-wide frame */
  if (git_attr_system_is_enabled()) {
    e = read_attr_from_file(git_attr_system_file(), flags);
    push_stack(stack, e, NULL, 0);
  }

  /* home directory */
  if (git_attr_global_file()) {
    e = read_attr_from_file(git_attr_global_file(), flags);
    push_stack(stack, e, NULL, 0);
  }

  /* root directory */
  e = read_attr(istate, tree_oid, GITATTRIBUTES_FILE, flags | READ_ATTR_NOFOLLOW);
  push_stack(stack, e, xstrdup(""), 0);

  /* info frame */
  if (startup_info->have_repository)
    e = read_attr_from_file(git_path_info_attributes(), flags);
  else
    e = NULL;
  if (!e)
    CALLOC_ARRAY(e, 1);
  push_stack(stack, e, NULL, 0);
}

static void prepare_attr_stack(struct index_state *istate,
             const struct object_id *tree_oid,
             const char *path, int dirlen,
             struct attr_stack **stack)
{
  struct attr_stack *info;
  struct strbuf pathbuf = STRBUF_INIT;

  /*
   * At the bottom of the attribute stack is the built-in
   * set of attribute definitions, followed by the contents
   * of $(prefix)/etc/gitattributes and a file specified by
   * core.attributesfile.  Then, contents from
   * .gitattributes files from directories closer to the
   * root to the ones in deeper directories are pushed
   * to the stack.  Finally, at the very top of the stack
   * we always keep the contents of $GIT_DIR/info/attributes.
   *
   * When checking, we use entries from near the top of the
   * stack, preferring $GIT_DIR/info/attributes, then
   * .gitattributes in deeper directories to shallower ones,
   * and finally use the built-in set as the default.
   */
  bootstrap_attr_stack(istate, tree_oid, stack);

  /*
   * Pop the "info" one that is always at the top of the stack.
   */
  info = *stack;
  *stack = info->prev;

  /*
   * Pop the ones from directories that are not the prefix of
   * the path we are checking. Break out of the loop when we see
   * the root one (whose origin is an empty string "") or the builtin
   * one (whose origin is NULL) without popping it.
   */
  while ((*stack)->origin) {
    int namelen = (*stack)->originlen;
    struct attr_stack *elem;

    elem = *stack;
    if (namelen <= dirlen &&
        !strncmp(elem->origin, path, namelen) &&
        (!namelen || path[namelen] == '/'))
      break;

    *stack = elem->prev;
    attr_stack_free(elem);
  }

  /*
   * bootstrap_attr_stack() should have added, and the
   * above loop should have stopped before popping, the
   * root element whose attr_stack->origin is set to an
   * empty string.
   */
  assert((*stack)->origin);

  strbuf_addstr(&pathbuf, (*stack)->origin);
  /* Build up to the directory 'path' is in */
  while (pathbuf.len < dirlen) {
    size_t len = pathbuf.len;
    struct attr_stack *next;
    char *origin;

    /* Skip path-separator */
    if (len < dirlen && is_dir_sep(path[len]))
      len++;
    /* Find the end of the next component */
    while (len < dirlen && !is_dir_sep(path[len]))
      len++;

    if (pathbuf.len > 0)
      strbuf_addch(&pathbuf, '/');
    strbuf_add(&pathbuf, path + pathbuf.len, (len - pathbuf.len));
    strbuf_addf(&pathbuf, "/%s", GITATTRIBUTES_FILE);

    next = read_attr(istate, tree_oid, pathbuf.buf, READ_ATTR_NOFOLLOW);

    /* reset the pathbuf to not include "/.gitattributes" */
    strbuf_setlen(&pathbuf, len);

    origin = xstrdup(pathbuf.buf);
    push_stack(stack, next, origin, len);
  }

  /*
   * Finally push the "info" one at the top of the stack.
   */
  push_stack(stack, info, NULL, 0);

  strbuf_release(&pathbuf);
}

static int path_matches(const char *pathname, int pathlen,
      int basename_offset,
      const struct pattern *pat,
      const char *base, int baselen)
{
  const char *pattern = pat->pattern;
  int prefix = pat->nowildcardlen;
  int isdir = (pathlen && pathname[pathlen - 1] == '/');

  if ((pat->flags & PATTERN_FLAG_MUSTBEDIR) && !isdir)
    return 0;

  if (pat->flags & PATTERN_FLAG_NODIR) {
    return match_basename(pathname + basename_offset,
              pathlen - basename_offset - isdir,
              pattern, prefix,
              pat->patternlen, pat->flags);
  }
  return match_pathname(pathname, pathlen - isdir,
            base, baselen,
            pattern, prefix, pat->patternlen);
}

static int macroexpand_one(struct all_attrs_item *all_attrs, int nr, int rem);

static int fill_one(struct all_attrs_item *all_attrs,
        const struct match_attr *a, int rem)
{
  size_t i;

  for (i = a->num_attr; rem > 0 && i > 0; i--) {
    const struct git_attr *attr = a->state[i - 1].attr;
    const char **n = &(all_attrs[attr->attr_nr].value);
    const char *v = a->state[i - 1].setto;

    if (*n == ATTR__UNKNOWN) {
      *n = v;
      rem--;
      rem = macroexpand_one(all_attrs, attr->attr_nr, rem);
    }
  }
  return rem;
}

static int fill(const char *path, int pathlen, int basename_offset,
    const struct attr_stack *stack,
    struct all_attrs_item *all_attrs, int rem)
{
  for (; rem > 0 && stack; stack = stack->prev) {
    unsigned i;
    const char *base = stack->origin ? stack->origin : "";

    for (i = stack->num_matches; 0 < rem && 0 < i; i--) {
      const struct match_attr *a = stack->attrs[i - 1];
      if (a->is_macro)
        continue;
      if (path_matches(path, pathlen, basename_offset,
           &a->u.pat, base, stack->originlen))
        rem = fill_one(all_attrs, a, rem);
    }
  }

  return rem;
}

static int macroexpand_one(struct all_attrs_item *all_attrs, int nr, int rem)
{
  const struct all_attrs_item *item = &all_attrs[nr];

  if (item->macro && item->value == ATTR__TRUE)
    return fill_one(all_attrs, item->macro, rem);
  else
    return rem;
}

/*
 * Marks the attributes which are macros based on the attribute stack.
 * This prevents having to search through the attribute stack each time
 * a macro needs to be expanded during the fill stage.
 */
static void determine_macros(struct all_attrs_item *all_attrs,
           const struct attr_stack *stack)
{
  for (; stack; stack = stack->prev) {
    unsigned i;
    for (i = stack->num_matches; i > 0; i--) {
      const struct match_attr *ma = stack->attrs[i - 1];
      if (ma->is_macro) {
        unsigned int n = ma->u.attr->attr_nr;
        if (!all_attrs[n].macro) {
          all_attrs[n].macro = ma;
        }
      }
    }
  }
}

/*
 * Collect attributes for path into the array pointed to by check->all_attrs.
 * If check->check_nr is non-zero, only attributes in check[] are collected.
 * Otherwise all attributes are collected.
 */
static void collect_some_attrs(struct index_state *istate,
             const struct object_id *tree_oid,
             const char *path, struct attr_check *check)
{
  int pathlen, rem, dirlen;
  const char *cp, *last_slash = NULL;
  int basename_offset;

  for (cp = path; *cp; cp++) {
    if (*cp == '/' && cp[1])
      last_slash = cp;
  }
  pathlen = cp - path;
  if (last_slash) {
    basename_offset = last_slash + 1 - path;
    dirlen = last_slash - path;
  } else {
    basename_offset = 0;
    dirlen = 0;
  }

  prepare_attr_stack(istate, tree_oid, path, dirlen, &check->stack);
  all_attrs_init(&g_attr_hashmap, check);
  determine_macros(check->all_attrs, check->stack);

  rem = check->all_attrs_nr;
  fill(path, pathlen, basename_offset, check->stack, check->all_attrs, rem);
}

static const char *default_attr_source_tree_object_name;

void set_git_attr_source(const char *tree_object_name)
{
  default_attr_source_tree_object_name = xstrdup(tree_object_name);
}

static int compute_default_attr_source(struct object_id *attr_source)
{
  int ignore_bad_attr_tree = 0;

  if (!default_attr_source_tree_object_name)
    default_attr_source_tree_object_name = getenv(GIT_ATTR_SOURCE_ENVIRONMENT);

  if (!default_attr_source_tree_object_name && git_attr_tree) {
    default_attr_source_tree_object_name = git_attr_tree;
    ignore_bad_attr_tree = 1;
  }

  if (!default_attr_source_tree_object_name)
    return 0;

  if (!startup_info->have_repository) {
    if (!ignore_bad_attr_tree)
      die(_("cannot use --attr-source or GIT_ATTR_SOURCE without repo"));
    return 0;
  }

  if (repo_get_oid_treeish(the_repository,
         default_attr_source_tree_object_name,
         attr_source)) {
    if (!ignore_bad_attr_tree)
      die(_("bad --attr-source or GIT_ATTR_SOURCE"));
    return 0;
  }

  return 1;
}

static struct object_id *default_attr_source(void)
{
  static struct object_id attr_source;
  static int has_attr_source = -1;

  if (has_attr_source < 0)
    has_attr_source = compute_default_attr_source(&attr_source);
  if (!has_attr_source)
    return NULL;
  return &attr_source;
}

static const char *interned_mode_string(unsigned int mode)
{
  static struct {
    unsigned int val;
    char str[7];
  } mode_string[] = {
    { .val = 0040000 },
    { .val = 0100644 },
    { .val = 0100755 },
    { .val = 0120000 },
    { .val = 0160000 },
  };
  int i;

  for (i = 0; i < ARRAY_SIZE(mode_string); i++) {
    if (mode_string[i].val != mode)
      continue;
    if (!*mode_string[i].str)
      snprintf(mode_string[i].str, sizeof(mode_string[i].str),
         "%06o", mode);
    return mode_string[i].str;
  }
  BUG("Unsupported mode 0%o", mode);
}

static const char *builtin_object_mode_attr(struct index_state *istate, const char *path)
{
  unsigned int mode;

  if (direction == GIT_ATTR_CHECKIN) {
    struct object_id oid;
    struct stat st;
    if (lstat(path, &st))
      die_errno(_("unable to stat '%s'"), path);
    mode = canon_mode(st.st_mode);
    if (S_ISDIR(mode)) {
      /*
       *`path` is either a directory or it is a submodule,
       * in which case it is already indexed as submodule
       * or it does not exist in the index yet and we need to
       * check if we can resolve to a ref.
      */
      int pos = index_name_pos(istate, path, strlen(path));
      if (pos >= 0) {
         if (S_ISGITLINK(istate->cache[pos]->ce_mode))
           mode = istate->cache[pos]->ce_mode;
      } else if (repo_resolve_gitlink_ref(the_repository, path,
                  "HEAD", &oid) == 0) {
        mode = S_IFGITLINK;
      }
    }
  } else {
    /*
     * For GIT_ATTR_CHECKOUT and GIT_ATTR_INDEX we only check
     * for mode in the index.
     */
    int pos = index_name_pos(istate, path, strlen(path));
    if (pos >= 0)
      mode = istate->cache[pos]->ce_mode;
    else
      return ATTR__UNSET;
  }

  return interned_mode_string(mode);
}


static const char *compute_builtin_attr(struct index_state *istate,
            const char *path,
            const struct git_attr *attr) {
  static const struct git_attr *object_mode_attr;

  if (!object_mode_attr)
    object_mode_attr = git_attr("builtin_objectmode");

  if (attr == object_mode_attr)
    return builtin_object_mode_attr(istate, path);
  return ATTR__UNSET;
}

void git_check_attr(struct index_state *istate,
        const char *path,
        struct attr_check *check)
{
  int i;
  const struct object_id *tree_oid = default_attr_source();

  collect_some_attrs(istate, tree_oid, path, check);

  for (i = 0; i < check->nr; i++) {
    unsigned int n = check->items[i].attr->attr_nr;
    const char *value = check->all_attrs[n].value;
    if (value == ATTR__UNKNOWN)
      value = compute_builtin_attr(istate, path, check->all_attrs[n].attr);
    check->items[i].value = value;
  }
}

void git_all_attrs(struct index_state *istate,
       const char *path, struct attr_check *check)
{
  int i;
  const struct object_id *tree_oid = default_attr_source();

  attr_check_reset(check);
  collect_some_attrs(istate, tree_oid, path, check);

  for (i = 0; i < check->all_attrs_nr; i++) {
    const char *name = check->all_attrs[i].attr->name;
    const char *value = check->all_attrs[i].value;
    struct attr_check_item *item;
    if (value == ATTR__UNSET || value == ATTR__UNKNOWN)
      continue;
    item = attr_check_append(check, git_attr(name));
    item->value = value;
  }
}

void attr_start(void)
{
  pthread_mutex_init(&g_attr_hashmap.mutex, NULL);
  pthread_mutex_init(&check_vector.mutex, NULL);
}

Coverage Report

Created: 2024-09-08 06:23