text: /* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
  
  /*  Fluent Bit
   *  ==========
   *  Copyright (C) 2019-2020 The Fluent Bit Authors
   *  Copyright (C) 2015-2018 Treasure Data Inc.
   *
   *  Licensed under the Apache License, Version 2.0 (the "License");
   *  you may not use this file except in compliance with the License.
   *  You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   *  Unless required by applicable law or agreed to in writing, software
   *  distributed under the License is distributed on an "AS IS" BASIS,
   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *  See the License for the specific language governing permissions and
   *  limitations under the License.
   */
  
  #include <sys/types.h>
  #include <sys/stat.h>
  #include <glob.h>
  #include <fnmatch.h>
  
  #include <fluent-bit/flb_compat.h>
  #include <fluent-bit/flb_input.h>
  #include <fluent-bit/flb_utils.h>
  
  #include "tail.h"
  #include "tail_file.h"
  #include "tail_signal.h"
  #include "tail_config.h"
  
  /* Define missing GLOB_TILDE if not exists */
  #ifndef GLOB_TILDE
  #define GLOB_TILDE    1<<2 /* use GNU Libc value */
  #define UNSUP_TILDE   1
  
  /* we need these extra headers for path resolution */
  #include <limits.h>
  #include <sys/types.h>
  #include <pwd.h>
  
  static char *expand_tilde(const char *path)
  {
      int len;
      char user[256];
      char *p = NULL;
      char *dir = NULL;
      char *tmp = NULL;
      struct passwd *uinfo = NULL;
  
      if (path[0] == '~') {
          p = strchr(path, '/');
  
          if (p) {
              /* check case '~/' */
              if ((p - path) == 1) {
                  dir = getenv("HOME");
                  if (!dir) {
                      return path;
                  }
              }
              else {
                  /*
                   * it refers to a different user: ~user/abc, first step grab
                   * the user name.
                   */
                  len = (p - path) - 1;
                  memcpy(user, path + 1, len);
                  user[len] = '\0';
  
                  /* use getpwnam() to resolve user information */
                  uinfo = getpwnam(user);
                  if (!uinfo) {
                      return path;
                  }
  
                  dir = uinfo->pw_dir;
              }
          }
          else {
              dir = getenv("HOME");
              if (!dir) {
                  return path;
              }
          }
  
          if (p) {
              tmp = flb_malloc(PATH_MAX);
              if (!tmp) {
                  flb_errno();
                  return NULL;
              }
              snprintf(tmp, PATH_MAX - 1, "%s%s", dir, p);
          }
          else {
              dir = getenv("HOME");
              if (!dir) {
                  return path;
              }
  
              tmp = flb_strdup(dir);
              if (!tmp) {
                  return path;
              }
          }
  
          return tmp;
      }
  
      return path;
  }
  #endif
  
  static inline int do_glob(const char *pattern, int flags,
                            void *not_used, glob_t *pglob)
  {
      int ret;
      int new_flags;
      char *tmp = NULL;
      (void) not_used;
  
      /* Save current values */
      new_flags = flags;
  
      if (flags & GLOB_TILDE) {
  #ifdef UNSUP_TILDE
          /*
           * Some libc libraries like Musl do not support GLOB_TILDE for tilde
           * expansion. A workaround is to use wordexp(3) but looking at it
           * implementation in Musl it looks quite expensive:
           *
           *  http://git.musl-libc.org/cgit/musl/tree/src/misc/wordexp.c
           *
           * the workaround is to do our own tilde expansion in a temporary buffer.
           */
  
          /* Look for a tilde */
          tmp = expand_tilde(pattern);
          if (tmp != pattern) {
              /* the path was expanded */
              pattern = tmp;
          }
  
          /* remove unused flag */
          new_flags &= ~GLOB_TILDE;
  #endif
      }
  
      /* invoke glob with new parameters */
      ret = glob(pattern, new_flags, NULL, pglob);
  
      /* remove temporary buffer, if allocated by expand_tilde above.
       * Note that this buffer is only used for libc implementations
       * that do not support the GLOB_TILDE flag, like musl. */
      if (tmp != NULL && tmp != pattern) {
          flb_free(tmp);
      }
  
      return ret;
  }
  
  static int tail_exclude_generate(struct flb_tail_config *ctx)
  {
      struct mk_list *list;
  
      /*
       * The exclusion path might content multiple exclusion patterns, first
       * let's split the content into a list.
       */
      list = flb_utils_split(ctx->exclude_path, ',', -1);
      if (!list) {
          return -1;
      }
  
      if (mk_list_is_empty(list) == 0) {
          return 0;
      }
  
      /* We use the same list head returned by flb_utils_split() */
      ctx->exclude_list = list;
      return 0;
  }
  
  static int tail_is_excluded(char *name, struct flb_tail_config *ctx)
  {
      struct mk_list *head;
      struct flb_split_entry *pattern;
  
      if (!ctx->exclude_list) {
          return FLB_FALSE;
      }
  
      mk_list_foreach(head, ctx->exclude_list) {
          pattern = mk_list_entry(head, struct flb_split_entry, _head);
          if (fnmatch(pattern->value, name, 0) == 0) {
              return FLB_TRUE;
          }
      }
  
      return FLB_FALSE;
  }
  
  /* Scan a path, register the entries and return how many */
  int flb_tail_scan(const char *path, struct flb_tail_config *ctx)
  {
      int i;
      int ret;
      int count = 0;
      glob_t globbuf;
      struct stat st;
  
      flb_debug("[in_tail] scanning path %s", path);
  
      /* Generate exclusion list */
      if (ctx->exclude_path) {
          tail_exclude_generate(ctx);
      }
  
      /* Safe reset for globfree() */
      globbuf.gl_pathv = NULL;
  
      /* Scan the given path */
      ret = do_glob(path, GLOB_TILDE | GLOB_ERR, NULL, &globbuf);
      if (ret != 0) {
          switch (ret) {
          case GLOB_NOSPACE:
              flb_error("[in_tail] no memory space available");
              return -1;
          case GLOB_ABORTED:
              flb_error("[in_tail] read error, check permissions: %s", path);
              return -1;
          case GLOB_NOMATCH:
              ret = stat(path, &st);
              if (ret == -1) {
                  flb_debug("[in_tail] Cannot read info from: %s", path);
              }
              else {
                  ret = access(path, R_OK);
                  if (ret == -1 && errno == EACCES) {
                      flb_error("[in_tail] NO read access for path: %s", path);
                  }
                  else {
                      flb_debug("[in_tail] NO matches for path: %s", path);
                  }
              }
              return 0;
          }
      }
  
      /* For every entry found, generate an output list */
      for (i = 0; i < globbuf.gl_pathc; i++) {
          ret = stat(globbuf.gl_pathv[i], &st);
          if (ret == 0 && S_ISREG(st.st_mode)) {
              /* Check if this file is blacklisted */
              if (tail_is_excluded(globbuf.gl_pathv[i], ctx) == FLB_TRUE) {
                  flb_debug("[in_tail] excluded=%s", globbuf.gl_pathv[i]);
                  continue;
              }
  
              /* Append file to list */
              flb_tail_file_append(globbuf.gl_pathv[i], &st,
                                   FLB_TAIL_STATIC, ctx);
              count++;
          }
          else {
              flb_debug("[in_tail] skip (invalid) entry=%s", globbuf.gl_pathv[i]);
          }
      }
  
      globfree(&globbuf);
      return 0;
  }
  
  /*
   * Triggered by refresh_interval, it re-scan the path looking for new files
   * that match the original path pattern.
   */
  int flb_tail_scan_callback(struct flb_input_instance *i_ins,
                             struct flb_config *config, void *context)
  {
      int i;
      int ret;
      int count = 0;
      glob_t globbuf;
      struct stat st;
      struct flb_tail_config *ctx = context;
      (void) config;
  
      /* Scan the path */
      ret = do_glob(ctx->path, GLOB_TILDE, NULL, &globbuf);
      if (ret != 0) {
          switch (ret) {
          case GLOB_NOSPACE:
              flb_error("[in_tail] no memory space available");
              return -1;
          case GLOB_ABORTED:
              flb_error("[in_tail] read error (GLOB_ABORTED");
              return -1;
          case GLOB_NOMATCH:
              return 0;
          }
      }
  
      /* For every entry found, check if is already registered or not */
      for (i = 0; i < globbuf.gl_pathc; i++) {
          ret = stat(globbuf.gl_pathv[i], &st);
          if (ret == 0 && S_ISREG(st.st_mode)) {
              /* Check if this file is blacklisted */
              if (tail_is_excluded(globbuf.gl_pathv[i], ctx) == FLB_TRUE) {
                  continue;
              }
  
              ret = flb_tail_file_exists(globbuf.gl_pathv[i], ctx);
              if (ret == FLB_TRUE) {
                  continue;
              }
  
              /* Append file to list */
              if (flb_tail_file_append(globbuf.gl_pathv[i], &st,
                                       FLB_TAIL_STATIC, ctx)) {
                  continue;
              }
  
              flb_debug("[in_tail] append new file: %s", globbuf.gl_pathv[i]);
  
              count++;
          }
          else {
              flb_debug("[in_tail] skip (invalid) entry=%s", globbuf.gl_pathv[i]);
          }
      }
  
      if (globbuf.gl_pathc > 0) {
          globfree(&globbuf);
      }
  
  
      if (count > 0) {
          tail_signal_manager(ctx);
      }
  
      return 0;
  }
  