Don't assume that succeeding libc calls don't modify errno

diff --git a/lockfile.c b/lockfile.c
index af4fa43af406098bd30644ff40db3846164fa1ca..f4f2028b7d612ae442d69c40d7484900ecd79a92 100644 (file)
--- a/lockfile.c
+++ b/lockfile.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2010-2014 Joel Rosdahl
+ * Copyright (C) 2010-2015 Joel Rosdahl
  *
  * 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 the Free
@@ -31,6 +31,7 @@
 bool
 lockfile_acquire(const char *path, unsigned staleness_limit)
 {
+       int saved_errno = 0;
        char *lockfile = format("%s.lock", path);
        char *my_content = NULL, *content = NULL, *initial_content = NULL;
        const char *hostname = get_hostname();
@@ -50,15 +51,16 @@ lockfile_acquire(const char *path, unsigned staleness_limit)
 #ifdef _WIN32
                fd = open(lockfile, O_WRONLY|O_CREAT|O_EXCL|O_BINARY, 0666);
                if (fd == -1) {
+                       saved_errno = errno;
                        cc_log("lockfile_acquire: open WRONLY %s: %s", lockfile, strerror(errno));
-                       if (errno == ENOENT) {
+                       if (saved_errno == ENOENT) {
                                /* Directory doesn't exist? */
                                if (create_parent_dirs(lockfile) == 0) {
                                        /* OK. Retry. */
                                        continue;
                                }
                        }
-                       if (errno != EEXIST) {
+                       if (saved_errno != EEXIST) {
                                /* Directory doesn't exist or isn't writable? */
                                goto out;
                        }
@@ -105,15 +107,16 @@ lockfile_acquire(const char *path, unsigned staleness_limit)
                        acquired = true;
                        goto out;
                }
-               cc_log("lockfile_acquire: symlink %s: %s", lockfile, strerror(errno));
-               if (errno == ENOENT) {
+               saved_errno = errno;
+               cc_log("lockfile_acquire: symlink %s: %s", lockfile, strerror(saved_errno));
+               if (saved_errno == ENOENT) {
                        /* Directory doesn't exist? */
                        if (create_parent_dirs(lockfile) == 0) {
                                /* OK. Retry. */
                                continue;
                        }
                }
-               if (errno == EPERM) {
+               if (saved_errno == EPERM) {
                        /*
                         * The file system does not support symbolic links. We have no choice but
                         * to grant the lock anyway.
@@ -121,7 +124,7 @@ lockfile_acquire(const char *path, unsigned staleness_limit)
                        acquired = true;
                        goto out;
                }
-               if (errno != EEXIST) {
+               if (saved_errno != EEXIST) {
                        /* Directory doesn't exist or isn't writable? */
                        goto out;
                }

diff --git a/util.c b/util.c
index 8b53705105d0f933bcd78ff3c5a10516c3706257..658cab6a94a875d37db66c30796bccfa2e3a7799 100644 (file)
--- a/util.c
+++ b/util.c
@@ -261,7 +261,8 @@ get_umask(void)
 
 /*
  * Copy src to dest, decompressing src if needed. compress_level > 0 decides
- * whether dest will be compressed, and with which compression level.
+ * whether dest will be compressed, and with which compression level. Returns 0
+ * on success and -1 on failure. On failure, errno represents the error.
  */
 int
 copy_file(const char *src, const char *dest, int compress_level)
@@ -273,6 +274,7 @@ copy_file(const char *src, const char *dest, int compress_level)
        char *tmp_name;
        struct stat st;
        int errnum;
+       int saved_errno = 0;
 
        /* open destination file */
        tmp_name = x_strdup(dest);
@@ -283,13 +285,15 @@ copy_file(const char *src, const char *dest, int compress_level)
        /* open source file */
        fd_in = open(src, O_RDONLY | O_BINARY);
        if (fd_in == -1) {
-               cc_log("open error: %s", strerror(errno));
+               saved_errno = errno;
+               cc_log("open error: %s", strerror(saved_errno));
                goto error;
        }
 
        gz_in = gzdopen(fd_in, "rb");
        if (!gz_in) {
-               cc_log("gzdopen(src) error: %s", strerror(errno));
+               saved_errno = errno;
+               cc_log("gzdopen(src) error: %s", strerror(saved_errno));
                close(fd_in);
                goto error;
        }
@@ -311,7 +315,8 @@ copy_file(const char *src, const char *dest, int compress_level)
        if (compress_level > 0) {
                gz_out = gzdopen(dup(fd_out), "wb");
                if (!gz_out) {
-                       cc_log("gzdopen(dest) error: %s", strerror(errno));
+                       saved_errno = errno;
+                       cc_log("gzdopen(dest) error: %s", strerror(saved_errno));
                        goto error;
                }
                gzsetparams(gz_out, compress_level, Z_DEFAULT_STRATEGY);
@@ -326,6 +331,7 @@ copy_file(const char *src, const char *dest, int compress_level)
                        do {
                                count = write(fd_out, buf + written, n - written);
                                if (count == -1 && errno != EINTR) {
+                                       saved_errno = errno;
                                        break;
                                }
                                written += count;
@@ -335,9 +341,9 @@ copy_file(const char *src, const char *dest, int compress_level)
                        if (compress_level > 0) {
                                cc_log("gzwrite error: %s (errno: %s)",
                                       gzerror(gz_in, &errnum),
-                                      strerror(errno));
+                                      strerror(saved_errno));
                        } else {
-                               cc_log("write error: %s", strerror(errno));
+                               cc_log("write error: %s", strerror(saved_errno));
                        }
                        goto error;
                }
@@ -349,8 +355,9 @@ copy_file(const char *src, const char *dest, int compress_level)
         */
        gzerror(gz_in, &errnum);
        if (!gzeof(gz_in) || (errnum != Z_OK && errnum != Z_STREAM_END)) {
+               saved_errno = errno;
                cc_log("gzread error: %s (errno: %s)",
-                      gzerror(gz_in, &errnum), strerror(errno));
+                      gzerror(gz_in, &errnum), strerror(saved_errno));
                gzclose(gz_in);
                if (gz_out) {
                        gzclose(gz_out);
@@ -374,12 +381,14 @@ copy_file(const char *src, const char *dest, int compress_level)
 
        /* the close can fail on NFS if out of space */
        if (close(fd_out) == -1) {
-               cc_log("close error: %s", strerror(errno));
+               saved_errno = errno;
+               cc_log("close error: %s", strerror(saved_errno));
                goto error;
        }
 
        if (x_rename(tmp_name, dest) == -1) {
-               cc_log("rename error: %s", strerror(errno));
+               saved_errno = errno;
+               cc_log("rename error: %s", strerror(saved_errno));
                goto error;
        }
 
@@ -399,6 +408,7 @@ error:
        }
        tmp_unlink(tmp_name);
        free(tmp_name);
+       errno = saved_errno;
        return -1;
 }
 
@@ -1488,7 +1498,7 @@ x_unlink(const char *path)
         */
        char *tmp_name = format("%s.rm.%s", path, tmp_string());
        int result = 0;
-       int saved_errno;
+       int saved_errno = 0;
        cc_log("Unlink %s via %s", path, tmp_name);
        if (x_rename(path, tmp_name) == -1) {
                result = -1;
@@ -1507,6 +1517,7 @@ out:
        if (result) {
                cc_log("x_unlink failed: %s", strerror(saved_errno));
        }
+       errno = saved_errno;
        return result;
 }