From dd8aa60346fc93beac5077d9a4e3a5b281df9085 Mon Sep 17 00:00:00 2001 From: Jim Meyering Date: Sat, 2 Jan 1999 05:16:57 +0000 Subject: [PATCH] (make_dir): New function, factored out of make_path. (make_path): Use make_dir rather than open-coding it twice. This effectively reverses the order of the latter pair of stat/mkdir calls and fixes a race condition bug whereby one of two concurrent `mkdir -p' processes could fail with EEXIST. --- lib/makepath.c | 95 ++++++++++++++++++++++++++++++++++++---------------------- 1 file changed, 60 insertions(+), 35 deletions(-) diff --git a/lib/makepath.c b/lib/makepath.c index 99119a213..cf570d9ac 100644 --- a/lib/makepath.c +++ b/lib/makepath.c @@ -1,5 +1,5 @@ /* makepath.c -- Ensure that a directory path exists. - Copyright (C) 1990, 1997, 1998 Free Software Foundation, Inc. + Copyright (C) 1990, 1997, 1998, 1999 Free Software Foundation, Inc. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -99,9 +99,9 @@ void strip_trailing_slashes (); Restore working directory. */ \ if (do_chdir) \ { \ - int fail = restore_cwd (&cwd, NULL, NULL); \ + int _fail = restore_cwd (&cwd, NULL, NULL); \ free_cwd (&cwd); \ - if (fail) \ + if (_fail) \ return 1; \ } \ } \ @@ -115,6 +115,56 @@ void strip_trailing_slashes (); } \ while (0) +/* Attempt to create directory DIR (aka DIRPATH) with the specified MODE. + If CREATED_DIR_P is non-NULL, set *CREATED_DIR_P to non-zero if this + function creates DIR and to zero otherwise. Give a diagnostic and + return non-zero if DIR cannot be created or cannot be determined to + exist already. Use DIRPATH in any diagnostic, not DIR. + Note that if DIR already exists, this function will return zero + (indicating success) and will set *CREATED_DIR_P to zero. */ + +static int +make_dir (const char *dir, const char *dirpath, mode_t mode, int *created_dir_p) +{ + int fail = 0; + int created_dir; + + created_dir = (mkdir (dir, mode) == 0); + + if (!created_dir) + { + struct stat stats; + + /* The mkdir and stat calls below may appear to be reversed. + They are not. It is important to call mkdir first and then to + call stat (to distinguish the three cases) only if mkdir fails. + The alternative to this approach is to `stat' each directory, + then to call mkdir if it doesn't exist. But if some other process + were to create the directory between the stat & mkdir, the mkdir + would fail with EEXIST. */ + + if (stat (dir, &stats)) + { + error (0, errno, "cannot create directory `%s'", dirpath); + fail = 1; + } + else if (!S_ISDIR (stats.st_mode)) + { + error (0, 0, "`%s' exists but is not a directory", dirpath); + fail = 1; + } + else + { + /* DIR (aka DIRPATH) already exists and is a directory. */ + } + } + + if (created_dir_p) + *created_dir_p = created_dir; + + return fail; +} + /* Ensure that the directory ARGPATH exists. Remove any trailing slashes from ARGPATH before calling this function. @@ -203,7 +253,8 @@ make_path (const char *argpath, while (1) { - int newly_created_dir = 1; + int newly_created_dir; + int fail; /* slash points to the leftmost unprocessed component of dirpath. */ basename_dir = slash; @@ -217,34 +268,12 @@ make_path (const char *argpath, if (!do_chdir) basename_dir = dirpath; - /* The mkdir and stat calls below appear to be reversed. - They are not. It is important to call mkdir first and then to - call stat (to distinguish the three cases) only if mkdir fails. - The alternative to this approach is to `stat' each directory, - then to call mkdir if it doesn't exist. But if some other process - were to create the directory between the stat & mkdir, the mkdir - would fail with EEXIST. */ - *slash = '\0'; - if (mkdir (basename_dir, tmp_mode)) + fail = make_dir (basename_dir, dirpath, tmp_mode, &newly_created_dir); + if (fail) { - if (stat (basename_dir, &stats)) - { - error (0, errno, "cannot create directory `%s'", dirpath); - CLEANUP; - return 1; - } - else if (!S_ISDIR (stats.st_mode)) - { - error (0, 0, "`%s' exists but is not a directory", dirpath); - CLEANUP; - return 1; - } - else - { - /* DIRPATH already exists and is a directory. */ - newly_created_dir = 0; - } + CLEANUP; + return 1; } if (newly_created_dir) @@ -299,12 +328,8 @@ make_path (const char *argpath, /* We're done making leading directories. Create the final component of the path. */ - /* The path could end in "/." or contain "/..", so test - if we really have to create the directory. */ - - if (stat (basename_dir, &stats) && mkdir (basename_dir, mode)) + if (make_dir (basename_dir, dirpath, mode, NULL)) { - error (0, errno, "cannot create directory `%s'", dirpath); CLEANUP; return 1; } -- 2.11.0