/*

 * Various trivial helper wrappers around standard functions

 */

#include "git-compat-util.h"

#include "abspath.h"

#include "parse.h"

#include "gettext.h"

#include "strbuf.h"

#include "trace2.h"

#ifdef HAVE_RTLGENRANDOM

/* This is required to get access to RtlGenRandom. */

#define SystemFunction036 NTAPI SystemFunction036

#include <ntsecapi.h>

#undef SystemFunction036

#endif

static int memory_limit_check(size_t size, int gentle)

{

  static size_t limit = 0;

  if (!limit) {

    limit = git_env_ulong("GIT_ALLOC_LIMIT", 0);

    if (!limit)

      limit = SIZE_MAX;

  }

  if (size > limit) {

    if (gentle) {

      error("attempting to allocate %"PRIuMAX" over limit %"PRIuMAX,

            (uintmax_t)size, (uintmax_t)limit);

      return -1;

    } else

      die("attempting to allocate %"PRIuMAX" over limit %"PRIuMAX,

          (uintmax_t)size, (uintmax_t)limit);

  }

  return 0;

}

char *xstrdup(const char *str)

{

  char *ret = strdup(str);

  if (!ret)

    die("Out of memory, strdup failed");

  return ret;

}

static void *do_xmalloc(size_t size, int gentle)

{

  void *ret;

  if (memory_limit_check(size, gentle))

    return NULL;

  ret = malloc(size);

  if (!ret && !size)

    ret = malloc(1);

  if (!ret) {

    if (!gentle)

      die("Out of memory, malloc failed (tried to allocate %lu bytes)",

          (unsigned long)size);

    else {

      error("Out of memory, malloc failed (tried to allocate %lu bytes)",

            (unsigned long)size);

      return NULL;

    }

  }

#ifdef XMALLOC_POISON

  memset(ret, 0xA5, size);

#endif

  return ret;

}

void *xmalloc(size_t size)

{

  return do_xmalloc(size, 0);

}

static void *do_xmallocz(size_t size, int gentle)

{

  void *ret;

  if (unsigned_add_overflows(size, 1)) {

    if (gentle) {

      error("Data too large to fit into virtual memory space.");

      return NULL;

    } else

      die("Data too large to fit into virtual memory space.");

  }

  ret = do_xmalloc(size + 1, gentle);

  if (ret)

    ((char*)ret)[size] = 0;

  return ret;

}

void *xmallocz(size_t size)

{

  return do_xmallocz(size, 0);

}

void *xmallocz_gently(size_t size)

{

  return do_xmallocz(size, 1);

}

/*

 * xmemdupz() allocates (len + 1) bytes of memory, duplicates "len" bytes of

 * "data" to the allocated memory, zero terminates the allocated memory,

 * and returns a pointer to the allocated memory. If the allocation fails,

 * the program dies.

 */

void *xmemdupz(const void *data, size_t len)

{

  return memcpy(xmallocz(len), data, len);

}

char *xstrndup(const char *str, size_t len)

{

  char *p = memchr(str, '\0', len);

  return xmemdupz(str, p ? p - str : len);

}

int xstrncmpz(const char *s, const char *t, size_t len)

{

  int res = strncmp(s, t, len);

  if (res)

    return res;

  return s[len] == '\0' ? 0 : 1;

}

void *xrealloc(void *ptr, size_t size)

{

  void *ret;

  if (!size) {

    free(ptr);

    return xmalloc(0);

  }

  memory_limit_check(size, 0);

  ret = realloc(ptr, size);

  if (!ret)

    die("Out of memory, realloc failed");

  return ret;

}

void *xcalloc(size_t nmemb, size_t size)

{

  void *ret;

  if (unsigned_mult_overflows(nmemb, size))

    die("data too large to fit into virtual memory space");

  memory_limit_check(size * nmemb, 0);

  ret = calloc(nmemb, size);

  if (!ret && (!nmemb || !size))

    ret = calloc(1, 1);

  if (!ret)

    die("Out of memory, calloc failed");

  return ret;

}

void xsetenv(const char *name, const char *value, int overwrite)

{

  if (setenv(name, value, overwrite))

    die_errno(_("could not setenv '%s'"), name ? name : "(null)");

}

/**

 * xopen() is the same as open(), but it die()s if the open() fails.

 */

int xopen(const char *path, int oflag, ...)

{

  mode_t mode = 0;

  va_list ap;

  /*

   * va_arg() will have undefined behavior if the specified type is not

   * compatible with the argument type. Since integers are promoted to

   * ints, we fetch the next argument as an int, and then cast it to a

   * mode_t to avoid undefined behavior.

   */

  va_start(ap, oflag);

  if (oflag & O_CREAT)

    mode = va_arg(ap, int);

  va_end(ap);

  for (;;) {

    int fd = open(path, oflag, mode);

    if (fd >= 0)

      return fd;

    if (errno == EINTR)

      continue;

    if ((oflag & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))

      die_errno(_("unable to create '%s'"), path);

    else if ((oflag & O_RDWR) == O_RDWR)

      die_errno(_("could not open '%s' for reading and writing"), path);

    else if ((oflag & O_WRONLY) == O_WRONLY)

      die_errno(_("could not open '%s' for writing"), path);

    else

      die_errno(_("could not open '%s' for reading"), path);

  }

}

static int handle_nonblock(int fd, short poll_events, int err)

{

  struct pollfd pfd;

  if (err != EAGAIN && err != EWOULDBLOCK)

    return 0;

  pfd.fd = fd;

  pfd.events = poll_events;

  /*

   * no need to check for errors, here;

   * a subsequent read/write will detect unrecoverable errors

   */

  poll(&pfd, 1, -1);

  return 1;

}

/*

 * xread() is the same a read(), but it automatically restarts read()

 * operations with a recoverable error (EAGAIN and EINTR). xread()

 * DOES NOT GUARANTEE that "len" bytes is read even if the data is available.

 */

ssize_t xread(int fd, void *buf, size_t len)

{

  ssize_t nr;

  if (len > MAX_IO_SIZE)

    len = MAX_IO_SIZE;

  while (1) {

    nr = read(fd, buf, len);

    if (nr < 0) {

      if (errno == EINTR)

        continue;

      if (handle_nonblock(fd, POLLIN, errno))

        continue;

    }

    return nr;

  }

}

/*

 * xwrite() is the same a write(), but it automatically restarts write()

 * operations with a recoverable error (EAGAIN and EINTR). xwrite() DOES NOT

 * GUARANTEE that "len" bytes is written even if the operation is successful.

 */

ssize_t xwrite(int fd, const void *buf, size_t len)

{

  ssize_t nr;

  if (len > MAX_IO_SIZE)

    len = MAX_IO_SIZE;

  while (1) {

    nr = write(fd, buf, len);

    if (nr < 0) {

      if (errno == EINTR)

        continue;

      if (handle_nonblock(fd, POLLOUT, errno))

        continue;

    }

    return nr;

  }

}

/*

 * xpread() is the same as pread(), but it automatically restarts pread()

 * operations with a recoverable error (EAGAIN and EINTR). xpread() DOES

 * NOT GUARANTEE that "len" bytes is read even if the data is available.

 */

ssize_t xpread(int fd, void *buf, size_t len, off_t offset)

{

  ssize_t nr;

  if (len > MAX_IO_SIZE)

    len = MAX_IO_SIZE;

  while (1) {

    nr = pread(fd, buf, len, offset);

    if ((nr < 0) && (errno == EAGAIN || errno == EINTR))

      continue;

    return nr;

  }

}

ssize_t read_in_full(int fd, void *buf, size_t count)

{

  char *p = buf;

  ssize_t total = 0;

  while (count > 0) {

    ssize_t loaded = xread(fd, p, count);

    if (loaded < 0)

      return -1;

    if (loaded == 0)

      return total;

    count -= loaded;

    p += loaded;

    total += loaded;

  }

  return total;

}

ssize_t write_in_full(int fd, const void *buf, size_t count)

{

  const char *p = buf;

  ssize_t total = 0;

  while (count > 0) {

    ssize_t written = xwrite(fd, p, count);

    if (written < 0)

      return -1;

    if (!written) {

      errno = ENOSPC;

      return -1;

    }

    count -= written;

    p += written;

    total += written;

  }

  return total;

}

ssize_t pread_in_full(int fd, void *buf, size_t count, off_t offset)

{

  char *p = buf;

  ssize_t total = 0;

  while (count > 0) {

    ssize_t loaded = xpread(fd, p, count, offset);

    if (loaded < 0)

      return -1;

    if (loaded == 0)

      return total;

    count -= loaded;

    p += loaded;

    total += loaded;

    offset += loaded;

  }

  return total;

}

int xdup(int fd)

{

  int ret = dup(fd);

  if (ret < 0)

    die_errno("dup failed");

  return ret;

}

/**

 * xfopen() is the same as fopen(), but it die()s if the fopen() fails.

 */

FILE *xfopen(const char *path, const char *mode)

{

  for (;;) {

    FILE *fp = fopen(path, mode);

    if (fp)

      return fp;

    if (errno == EINTR)

      continue;

    if (*mode && mode[1] == '+')

      die_errno(_("could not open '%s' for reading and writing"), path);

    else if (*mode == 'w' || *mode == 'a')

      die_errno(_("could not open '%s' for writing"), path);

    else

      die_errno(_("could not open '%s' for reading"), path);

  }

}

FILE *xfdopen(int fd, const char *mode)

{

  FILE *stream = fdopen(fd, mode);

  if (!stream)

    die_errno("Out of memory? fdopen failed");

  return stream;

}

FILE *fopen_for_writing(const char *path)

{

  FILE *ret = fopen(path, "w");

  if (!ret && errno == EPERM) {

    if (!unlink(path))

      ret = fopen(path, "w");

    else

      errno = EPERM;

  }

  return ret;

}

static void warn_on_inaccessible(const char *path)

{

  warning_errno(_("unable to access '%s'"), path);

}

int warn_on_fopen_errors(const char *path)

{

  if (errno != ENOENT && errno != ENOTDIR) {

    warn_on_inaccessible(path);

    return -1;

  }

  return 0;

}

FILE *fopen_or_warn(const char *path, const char *mode)

{

  FILE *fp = fopen(path, mode);

  if (fp)

    return fp;

  warn_on_fopen_errors(path);

  return NULL;

}

int xmkstemp(char *filename_template)

{

  int fd;

  char origtemplate[PATH_MAX];

  strlcpy(origtemplate, filename_template, sizeof(origtemplate));

  fd = mkstemp(filename_template);

  if (fd < 0) {

    int saved_errno = errno;

    const char *nonrelative_template;

    if (strlen(filename_template) != strlen(origtemplate))

      filename_template = origtemplate;

    nonrelative_template = absolute_path(filename_template);

    errno = saved_errno;

    die_errno("Unable to create temporary file '%s'",

      nonrelative_template);

  }

  return fd;

}

/* Adapted from libiberty's mkstemp.c. */

#undef TMP_MAX

#define TMP_MAX 16384

int git_mkstemps_mode(char *pattern, int suffix_len, int mode)

{

  static const char letters[] =

    "abcdefghijklmnopqrstuvwxyz"

    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

    "0123456789";

  static const int num_letters = ARRAY_SIZE(letters) - 1;

  static const char x_pattern[] = "XXXXXX";

  static const int num_x = ARRAY_SIZE(x_pattern) - 1;

  char *filename_template;

  size_t len;

  int fd, count;

  len = strlen(pattern);

  if (len < num_x + suffix_len) {

    errno = EINVAL;

    return -1;

  }

  if (strncmp(&pattern[len - num_x - suffix_len], x_pattern, num_x)) {

    errno = EINVAL;

    return -1;

  }

  /*

   * Replace pattern's XXXXXX characters with randomness.

   * Try TMP_MAX different filenames.

   */

  filename_template = &pattern[len - num_x - suffix_len];

  for (count = 0; count < TMP_MAX; ++count) {

    int i;

    uint64_t v;

    if (csprng_bytes(&v, sizeof(v)) < 0)

      return error_errno("unable to get random bytes for temporary file");

    /* Fill in the random bits. */

    for (i = 0; i < num_x; i++) {

      filename_template[i] = letters[v % num_letters];

      v /= num_letters;

    }

    fd = open(pattern, O_CREAT | O_EXCL | O_RDWR, mode);

    if (fd >= 0)

      return fd;

    /*

     * Fatal error (EPERM, ENOSPC etc).

     * It doesn't make sense to loop.

     */

    if (errno != EEXIST)

      break;

  }

  /* We return the null string if we can't find a unique file name.  */

  pattern[0] = '\0';

  return -1;

}

int git_mkstemp_mode(char *pattern, int mode)

{

  /* mkstemp is just mkstemps with no suffix */

  return git_mkstemps_mode(pattern, 0, mode);

}

int xmkstemp_mode(char *filename_template, int mode)

{

  int fd;

  char origtemplate[PATH_MAX];

  strlcpy(origtemplate, filename_template, sizeof(origtemplate));

  fd = git_mkstemp_mode(filename_template, mode);

  if (fd < 0) {

    int saved_errno = errno;

    const char *nonrelative_template;

    if (!filename_template[0])

      filename_template = origtemplate;

    nonrelative_template = absolute_path(filename_template);

    errno = saved_errno;

    die_errno("Unable to create temporary file '%s'",

      nonrelative_template);

  }

  return fd;

}

/*

 * Some platforms return EINTR from fsync. Since fsync is invoked in some

 * cases by a wrapper that dies on failure, do not expose EINTR to callers.

 */

static int fsync_loop(int fd)

{

  int err;

  do {

    err = fsync(fd);

  } while (err < 0 && errno == EINTR);

  return err;

}

int git_fsync(int fd, enum fsync_action action)

{

  switch (action) {

  case FSYNC_WRITEOUT_ONLY:

    trace2_counter_add(TRACE2_COUNTER_ID_FSYNC_WRITEOUT_ONLY, 1);

#ifdef __APPLE__

    /*

     * On macOS, fsync just causes filesystem cache writeback but

     * does not flush hardware caches.

     */

    return fsync_loop(fd);

#endif

#ifdef HAVE_SYNC_FILE_RANGE

    /*

     * On linux 2.6.17 and above, sync_file_range is the way to

     * issue a writeback without a hardware flush. An offset of

     * 0 and size of 0 indicates writeout of the entire file and the

     * wait flags ensure that all dirty data is written to the disk

     * (potentially in a disk-side cache) before we continue.

     */

    return sync_file_range(fd, 0, 0, SYNC_FILE_RANGE_WAIT_BEFORE |

             SYNC_FILE_RANGE_WRITE |

             SYNC_FILE_RANGE_WAIT_AFTER);

#endif

#ifdef fsync_no_flush

    return fsync_no_flush(fd);

#endif

    errno = ENOSYS;

    return -1;

  case FSYNC_HARDWARE_FLUSH:

    trace2_counter_add(TRACE2_COUNTER_ID_FSYNC_HARDWARE_FLUSH, 1);

    /*

     * On macOS, a special fcntl is required to really flush the

     * caches within the storage controller. As of this writing,

     * this is a very expensive operation on Apple SSDs.

     */

#ifdef __APPLE__

    return fcntl(fd, F_FULLFSYNC);

#else

    return fsync_loop(fd);

#endif

  default:

    BUG("unexpected git_fsync(%d) call", action);

  }

}

static int warn_if_unremovable(const char *op, const char *file, int rc)

{

  int err;

  if (!rc || errno == ENOENT)

    return 0;

  err = errno;

  warning_errno("unable to %s '%s'", op, file);

  errno = err;

  return rc;

}

int unlink_or_msg(const char *file, struct strbuf *err)

{

  int rc = unlink(file);

  assert(err);

  if (!rc || errno == ENOENT)

    return 0;

  strbuf_addf(err, "unable to unlink '%s': %s",

        file, strerror(errno));

  return -1;

}

int unlink_or_warn(const char *file)

{

  return warn_if_unremovable("unlink", file, unlink(file));

}

int rmdir_or_warn(const char *file)

{

  return warn_if_unremovable("rmdir", file, rmdir(file));

}

static int access_error_is_ok(int err, unsigned flag)

{

  return (is_missing_file_error(err) ||

    ((flag & ACCESS_EACCES_OK) && err == EACCES));

}

int access_or_warn(const char *path, int mode, unsigned flag)

{

  int ret = access(path, mode);

  if (ret && !access_error_is_ok(errno, flag))

    warn_on_inaccessible(path);

  return ret;

}

int access_or_die(const char *path, int mode, unsigned flag)

{

  int ret = access(path, mode);

  if (ret && !access_error_is_ok(errno, flag))

    die_errno(_("unable to access '%s'"), path);

  return ret;

}

char *xgetcwd(void)

{

  struct strbuf sb = STRBUF_INIT;

  if (strbuf_getcwd(&sb))

    die_errno(_("unable to get current working directory"));

  return strbuf_detach(&sb, NULL);

}

int xsnprintf(char *dst, size_t max, const char *fmt, ...)

{

  va_list ap;

  int len;

  va_start(ap, fmt);

  len = vsnprintf(dst, max, fmt, ap);

  va_end(ap);

  if (len < 0)

    die(_("unable to format message: %s"), fmt);

  if (len >= max)

    BUG("attempt to snprintf into too-small buffer");

  return len;

}

void write_file_buf(const char *path, const char *buf, size_t len)

{

  int fd = xopen(path, O_WRONLY | O_CREAT | O_TRUNC, 0666);

  if (write_in_full(fd, buf, len) < 0)

    die_errno(_("could not write to '%s'"), path);

  if (close(fd))

    die_errno(_("could not close '%s'"), path);

}

void write_file(const char *path, const char *fmt, ...)

{

  va_list params;

  struct strbuf sb = STRBUF_INIT;

  va_start(params, fmt);

  strbuf_vaddf(&sb, fmt, params);

  va_end(params);

  strbuf_complete_line(&sb);

  write_file_buf(path, sb.buf, sb.len);

  strbuf_release(&sb);

}

void sleep_millisec(int millisec)

{

  poll(NULL, 0, millisec);

}

int xgethostname(char *buf, size_t len)

{

  /*

   * If the full hostname doesn't fit in buf, POSIX does not

   * specify whether the buffer will be null-terminated, so to

   * be safe, do it ourselves.

   */

  int ret = gethostname(buf, len);

  if (!ret)

    buf[len - 1] = 0;

  return ret;

}

int is_empty_or_missing_file(const char *filename)

{

  struct stat st;

  if (stat(filename, &st) < 0) {

    if (errno == ENOENT)

      return 1;

    die_errno(_("could not stat %s"), filename);

  }

  return !st.st_size;

}

int open_nofollow(const char *path, int flags)

{

#ifdef O_NOFOLLOW

  return open(path, flags | O_NOFOLLOW);

#else

  struct stat st;

  if (lstat(path, &st) < 0)

    return -1;

  if (S_ISLNK(st.st_mode)) {

    errno = ELOOP;

    return -1;

  }

  return open(path, flags);

#endif

}

int csprng_bytes(void *buf, size_t len)

{

#if defined(HAVE_ARC4RANDOM) || defined(HAVE_ARC4RANDOM_LIBBSD)

  /* This function never returns an error. */

  arc4random_buf(buf, len);

  return 0;

#elif defined(HAVE_GETRANDOM)

  ssize_t res;

  char *p = buf;

  while (len) {

    res = getrandom(p, len, 0);

    if (res < 0)

      return -1;

    len -= res;

    p += res;

  }

  return 0;

#elif defined(HAVE_GETENTROPY)

  int res;

  char *p = buf;

  while (len) {

    /* getentropy has a maximum size of 256 bytes. */

    size_t chunk = len < 256 ? len : 256;

    res = getentropy(p, chunk);

    if (res < 0)

      return -1;

    len -= chunk;

    p += chunk;

  }

  return 0;

#elif defined(HAVE_RTLGENRANDOM)

  if (!RtlGenRandom(buf, len))

    return -1;

  return 0;

#elif defined(HAVE_OPENSSL_CSPRNG)

  int res = RAND_bytes(buf, len);

  if (res == 1)

    return 0;

  if (res == -1)

    errno = ENOTSUP;

  else

    errno = EIO;

  return -1;

#else

  ssize_t res;

  char *p = buf;

  int fd, err;

  fd = open("/dev/urandom", O_RDONLY);

  if (fd < 0)

    return -1;

  while (len) {

    res = xread(fd, p, len);

    if (res < 0) {

      err = errno;

      close(fd);

      errno = err;

      return -1;

    }

    len -= res;

    p += res;

  }

  close(fd);

  return 0;

#endif

}

uint32_t git_rand(void)

{

  uint32_t result;

  if (csprng_bytes(&result, sizeof(result)) < 0)

    die(_("unable to get random bytes"));

  return result;

}