#include "git-compat-util.h"

#include "abspath.h"

#include "sigchain.h"

#include "strbuf.h"

#include "trace2/tr2_dst.h"

#include "trace2/tr2_sid.h"

#include "trace2/tr2_sysenv.h"

/*

 * How many attempts we will make at creating an automatically-named trace file.

 */

#define MAX_AUTO_ATTEMPTS 10

/*

 * Sentinel file used to detect when we should discard new traces to avoid

 * writing too many trace files to a directory.

 */

#define DISCARD_SENTINEL_NAME "git-trace2-discard"

/*

 * When set to zero, disables directory file count checks. Otherwise, controls

 * how many files we can write to a directory before entering discard mode.

 * This can be overridden via the TR2_SYSENV_MAX_FILES setting.

 */

static int tr2env_max_files = 0;

static int tr2_dst_want_warning(void)

{

  static int tr2env_dst_debug = -1;

  if (tr2env_dst_debug == -1) {

    const char *env_value = tr2_sysenv_get(TR2_SYSENV_DST_DEBUG);

    if (!env_value || !*env_value)

      tr2env_dst_debug = 0;

    else

      tr2env_dst_debug = atoi(env_value) > 0;

  }

  return tr2env_dst_debug;

}

void tr2_dst_trace_disable(struct tr2_dst *dst)

{

  if (dst->need_close)

    close(dst->fd);

  dst->fd = 0;

  dst->initialized = 1;

  dst->need_close = 0;

}

/*

 * Check to make sure we're not overloading the target directory with too many

 * files. First get the threshold (if present) from the config or envvar. If

 * it's zero or unset, disable this check. Next check for the presence of a

 * sentinel file, then check file count.

 *

 * Returns 0 if tracing should proceed as normal. Returns 1 if the sentinel file

 * already exists, which means tracing should be disabled. Returns -1 if there

 * are too many files but there was no sentinel file, which means we have

 * created and should write traces to the sentinel file.

 *

 * We expect that some trace processing system is gradually collecting files

 * from the target directory; after it removes the sentinel file we'll start

 * writing traces again.

 */

static int tr2_dst_too_many_files(struct tr2_dst *dst, const char *tgt_prefix)

{

  int file_count = 0, max_files = 0, ret = 0;

  const char *max_files_var;

  DIR *dirp;

  struct strbuf path = STRBUF_INIT, sentinel_path = STRBUF_INIT;

  struct stat statbuf;

  /* Get the config or envvar and decide if we should continue this check */

  max_files_var = tr2_sysenv_get(TR2_SYSENV_MAX_FILES);

  if (max_files_var && *max_files_var && ((max_files = atoi(max_files_var)) >= 0))

    tr2env_max_files = max_files;

  if (!tr2env_max_files) {

    ret = 0;

    goto cleanup;

  }

  strbuf_addstr(&path, tgt_prefix);

  if (!is_dir_sep(path.buf[path.len - 1])) {

    strbuf_addch(&path, '/');

  }

  /* check sentinel */

  strbuf_addbuf(&sentinel_path, &path);

  strbuf_addstr(&sentinel_path, DISCARD_SENTINEL_NAME);

  if (!stat(sentinel_path.buf, &statbuf)) {

    ret = 1;

    goto cleanup;

  }

  /* check file count */

  dirp = opendir(path.buf);

  while (file_count < tr2env_max_files && dirp && readdir(dirp))

    file_count++;

  if (dirp)

    closedir(dirp);

  if (file_count >= tr2env_max_files) {

    dst->too_many_files = 1;

    dst->fd = open(sentinel_path.buf, O_WRONLY | O_CREAT | O_EXCL, 0666);

    ret = -1;

    goto cleanup;

  }

cleanup:

  strbuf_release(&path);

  strbuf_release(&sentinel_path);

  return ret;

}

static int tr2_dst_try_auto_path(struct tr2_dst *dst, const char *tgt_prefix)

{

  int too_many_files;

  const char *last_slash, *sid = tr2_sid_get();

  struct strbuf path = STRBUF_INIT;

  size_t base_path_len;

  unsigned attempt_count;

  last_slash = strrchr(sid, '/');

  if (last_slash)

    sid = last_slash + 1;

  strbuf_addstr(&path, tgt_prefix);

  if (!is_dir_sep(path.buf[path.len - 1]))

    strbuf_addch(&path, '/');

  strbuf_addstr(&path, sid);

  base_path_len = path.len;

  too_many_files = tr2_dst_too_many_files(dst, tgt_prefix);

  if (!too_many_files) {

    for (attempt_count = 0; attempt_count < MAX_AUTO_ATTEMPTS; attempt_count++) {

      if (attempt_count > 0) {

        strbuf_setlen(&path, base_path_len);

        strbuf_addf(&path, ".%d", attempt_count);

      }

      dst->fd = open(path.buf, O_WRONLY | O_CREAT | O_EXCL, 0666);

      if (dst->fd != -1)

        break;

    }

  } else if (too_many_files == 1) {

    strbuf_release(&path);

    if (tr2_dst_want_warning())

      warning("trace2: not opening %s trace file due to too "

        "many files in target directory %s",

        tr2_sysenv_display_name(dst->sysenv_var),

        tgt_prefix);

    return 0;

  }

  if (dst->fd == -1) {

    if (tr2_dst_want_warning())

      warning("trace2: could not open '%.*s' for '%s' tracing: %s",

        (int) base_path_len, path.buf,

        tr2_sysenv_display_name(dst->sysenv_var),

        strerror(errno));

    tr2_dst_trace_disable(dst);

    strbuf_release(&path);

    return 0;

  }

  strbuf_release(&path);

  dst->need_close = 1;

  dst->initialized = 1;

  return dst->fd;

}

static int tr2_dst_try_path(struct tr2_dst *dst, const char *tgt_value)

{

  int fd = open(tgt_value, O_WRONLY | O_APPEND | O_CREAT, 0666);

  if (fd == -1) {

    if (tr2_dst_want_warning())

      warning("trace2: could not open '%s' for '%s' tracing: %s",

        tgt_value,

        tr2_sysenv_display_name(dst->sysenv_var),

        strerror(errno));

    tr2_dst_trace_disable(dst);

    return 0;

  }

  dst->fd = fd;

  dst->need_close = 1;

  dst->initialized = 1;

  return dst->fd;

}

#ifndef NO_UNIX_SOCKETS

#define PREFIX_AF_UNIX "af_unix:"

#define PREFIX_AF_UNIX_STREAM "af_unix:stream:"

#define PREFIX_AF_UNIX_DGRAM "af_unix:dgram:"

static int tr2_dst_try_uds_connect(const char *path, int sock_type, int *out_fd)

{

  int fd;

  struct sockaddr_un sa;

  fd = socket(AF_UNIX, sock_type, 0);

  if (fd == -1)

    return -1;

  sa.sun_family = AF_UNIX;

  strlcpy(sa.sun_path, path, sizeof(sa.sun_path));

  if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {

    int saved_errno = errno;

    close(fd);

    errno = saved_errno;

    return -1;

  }

  *out_fd = fd;

  return 0;

}

#define TR2_DST_UDS_TRY_STREAM (1 << 0)

#define TR2_DST_UDS_TRY_DGRAM  (1 << 1)

static int tr2_dst_try_unix_domain_socket(struct tr2_dst *dst,

            const char *tgt_value)

{

  unsigned int uds_try = 0;

  int fd;

  const char *path = NULL;

  /*

   * Allow "af_unix:[<type>:]<absolute_path>"

   *

   * Trace2 always writes complete individual messages (without

   * chunking), so we can talk to either DGRAM or STREAM type sockets.

   *

   * Allow the user to explicitly request the socket type.

   *

   * If they omit the socket type, try one and then the other.

   */

  if (skip_prefix(tgt_value, PREFIX_AF_UNIX_STREAM, &path))

    uds_try |= TR2_DST_UDS_TRY_STREAM;

  else if (skip_prefix(tgt_value, PREFIX_AF_UNIX_DGRAM, &path))

    uds_try |= TR2_DST_UDS_TRY_DGRAM;

  else if (skip_prefix(tgt_value, PREFIX_AF_UNIX, &path))

    uds_try |= TR2_DST_UDS_TRY_STREAM | TR2_DST_UDS_TRY_DGRAM;

  if (!path || !*path) {

    if (tr2_dst_want_warning())

      warning("trace2: invalid AF_UNIX value '%s' for '%s' tracing",

        tgt_value,

        tr2_sysenv_display_name(dst->sysenv_var));

    tr2_dst_trace_disable(dst);

    return 0;

  }

  if (!is_absolute_path(path) ||

      strlen(path) >= sizeof(((struct sockaddr_un *)0)->sun_path)) {

    if (tr2_dst_want_warning())

      warning("trace2: invalid AF_UNIX path '%s' for '%s' tracing",

        path, tr2_sysenv_display_name(dst->sysenv_var));

    tr2_dst_trace_disable(dst);

    return 0;

  }

  if (uds_try & TR2_DST_UDS_TRY_STREAM) {

    if (!tr2_dst_try_uds_connect(path, SOCK_STREAM, &fd))

      goto connected;

    if (errno != EPROTOTYPE)

      goto error;

  }

  if (uds_try & TR2_DST_UDS_TRY_DGRAM) {

    if (!tr2_dst_try_uds_connect(path, SOCK_DGRAM, &fd))

      goto connected;

  }

error:

  if (tr2_dst_want_warning())

    warning("trace2: could not connect to socket '%s' for '%s' tracing: %s",

      path, tr2_sysenv_display_name(dst->sysenv_var),

      strerror(errno));

  tr2_dst_trace_disable(dst);

  return 0;

connected:

  dst->fd = fd;

  dst->need_close = 1;

  dst->initialized = 1;

  return dst->fd;

}

#endif

static void tr2_dst_malformed_warning(struct tr2_dst *dst,

              const char *tgt_value)

{

  warning("trace2: unknown value for '%s': '%s'",

    tr2_sysenv_display_name(dst->sysenv_var), tgt_value);

}

int tr2_dst_get_trace_fd(struct tr2_dst *dst)

{

  const char *tgt_value;

  /* don't open twice */

  if (dst->initialized)

    return dst->fd;

  dst->initialized = 1;

  tgt_value = tr2_sysenv_get(dst->sysenv_var);

  if (!tgt_value || !strcmp(tgt_value, "") || !strcmp(tgt_value, "0") ||

      !strcasecmp(tgt_value, "false")) {

    dst->fd = 0;

    return dst->fd;

  }

  if (!strcmp(tgt_value, "1") || !strcasecmp(tgt_value, "true")) {

    dst->fd = STDERR_FILENO;

    return dst->fd;

  }

  if (strlen(tgt_value) == 1 && isdigit(*tgt_value)) {

    dst->fd = atoi(tgt_value);

    return dst->fd;

  }

  if (is_absolute_path(tgt_value)) {

    if (is_directory(tgt_value))

      return tr2_dst_try_auto_path(dst, tgt_value);

    else

      return tr2_dst_try_path(dst, tgt_value);

  }

#ifndef NO_UNIX_SOCKETS

  if (starts_with(tgt_value, PREFIX_AF_UNIX))

    return tr2_dst_try_unix_domain_socket(dst, tgt_value);

#endif

  /* Always warn about malformed values. */

  tr2_dst_malformed_warning(dst, tgt_value);

  tr2_dst_trace_disable(dst);

  return 0;

}

int tr2_dst_trace_want(struct tr2_dst *dst)

{

  return !!tr2_dst_get_trace_fd(dst);

}

void tr2_dst_write_line(struct tr2_dst *dst, struct strbuf *buf_line)

{

  int fd = tr2_dst_get_trace_fd(dst);

  ssize_t bytes;

  strbuf_complete_line(buf_line); /* ensure final NL on buffer */

  /*

   * We do not use write_in_full() because we do not want

   * a short-write to try again.  We are using O_APPEND mode

   * files and the kernel handles the atomic seek+write. If

   * another thread or git process is concurrently writing to

   * this fd or file, our remainder-write may not be contiguous

   * with our initial write of this message.  And that will

   * confuse readers.  So just don't bother.

   *

   * It is assumed that TRACE2 messages are short enough that

   * the system can write them in 1 attempt and we won't see

   * a short-write.

   *

   * If we get an IO error, just close the trace dst.

   */

  sigchain_push(SIGPIPE, SIG_IGN);

  bytes = write(fd, buf_line->buf, buf_line->len);

  sigchain_pop(SIGPIPE);

  if (bytes >= 0)

    return;

  tr2_dst_trace_disable(dst);

  if (tr2_dst_want_warning())

    warning("unable to write trace to '%s': %s",

      tr2_sysenv_display_name(dst->sysenv_var),

      strerror(errno));

}