123 lines
4.4 KiB
Diff
123 lines
4.4 KiB
Diff
Revert to 6.0.8 behavior to save configuration file
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to fix "CONFIG REWRITE" when using /etc/redis.conf
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as new behavior expect a writable directory
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Revert: 90555566ed5cbd3e1c3df1293ba3bbf6098e34c3
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See discussion about this breaking change in
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https://github.com/redis/redis/issues/8051
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--- redis-6.0.9/src/config.c 2020-10-27 08:12:01.000000000 +0100
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+++ redis-6.0.8/src/config.c 2020-09-10 13:09:00.000000000 +0200
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@@ -1568,62 +1568,60 @@
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dictReleaseIterator(di);
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}
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-/* This function replaces the old configuration file with the new content
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- * in an atomic manner.
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+/* This function overwrites the old configuration file with the new content.
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+ *
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+ * 1) The old file length is obtained.
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+ * 2) If the new content is smaller, padding is added.
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+ * 3) A single write(2) call is used to replace the content of the file.
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+ * 4) Later the file is truncated to the length of the new content.
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+ *
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+ * This way we are sure the file is left in a consistent state even if the
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+ * process is stopped between any of the four operations.
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*
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* The function returns 0 on success, otherwise -1 is returned and errno
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- * is set accordingly. */
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+ * set accordingly. */
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int rewriteConfigOverwriteFile(char *configfile, sds content) {
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- int fd = -1;
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- int retval = -1;
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- char tmp_conffile[PATH_MAX];
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- const char *tmp_suffix = ".XXXXXX";
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- size_t offset = 0;
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- ssize_t written_bytes = 0;
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-
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- int tmp_path_len = snprintf(tmp_conffile, sizeof(tmp_conffile), "%s%s", configfile, tmp_suffix);
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- if (tmp_path_len <= 0 || (unsigned int)tmp_path_len >= sizeof(tmp_conffile)) {
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- serverLog(LL_WARNING, "Config file full path is too long");
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- errno = ENAMETOOLONG;
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- return retval;
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- }
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-
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-#ifdef _GNU_SOURCE
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- fd = mkostemp(tmp_conffile, O_CLOEXEC);
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-#else
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- /* There's a theoretical chance here to leak the FD if a module thread forks & execv in the middle */
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- fd = mkstemp(tmp_conffile);
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-#endif
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-
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- if (fd == -1) {
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- serverLog(LL_WARNING, "Could not create tmp config file (%s)", strerror(errno));
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- return retval;
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- }
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-
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- while (offset < sdslen(content)) {
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- written_bytes = write(fd, content + offset, sdslen(content) - offset);
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- if (written_bytes <= 0) {
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- if (errno == EINTR) continue; /* FD is blocking, no other retryable errors */
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- serverLog(LL_WARNING, "Failed after writing (%zd) bytes to tmp config file (%s)", offset, strerror(errno));
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- goto cleanup;
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- }
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- offset+=written_bytes;
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- }
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-
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- if (fsync(fd))
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- serverLog(LL_WARNING, "Could not sync tmp config file to disk (%s)", strerror(errno));
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- else if (fchmod(fd, 0644) == -1)
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- serverLog(LL_WARNING, "Could not chmod config file (%s)", strerror(errno));
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- else if (rename(tmp_conffile, configfile) == -1)
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- serverLog(LL_WARNING, "Could not rename tmp config file (%s)", strerror(errno));
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- else {
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- retval = 0;
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- serverLog(LL_DEBUG, "Rewritten config file (%s) successfully", configfile);
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+ int retval = 0;
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+ int fd = open(configfile,O_RDWR|O_CREAT,0644);
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+ int content_size = sdslen(content), padding = 0;
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+ struct stat sb;
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+ sds content_padded;
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+
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+ /* 1) Open the old file (or create a new one if it does not
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+ * exist), get the size. */
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+ if (fd == -1) return -1; /* errno set by open(). */
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+ if (fstat(fd,&sb) == -1) {
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+ close(fd);
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+ return -1; /* errno set by fstat(). */
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+ }
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+
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+ /* 2) Pad the content at least match the old file size. */
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+ content_padded = sdsdup(content);
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+ if (content_size < sb.st_size) {
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+ /* If the old file was bigger, pad the content with
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+ * a newline plus as many "#" chars as required. */
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+ padding = sb.st_size - content_size;
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+ content_padded = sdsgrowzero(content_padded,sb.st_size);
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+ content_padded[content_size] = '\n';
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+ memset(content_padded+content_size+1,'#',padding-1);
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+ }
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+
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+ /* 3) Write the new content using a single write(2). */
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+ if (write(fd,content_padded,strlen(content_padded)) == -1) {
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+ retval = -1;
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+ goto cleanup;
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+ }
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+
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+ /* 4) Truncate the file to the right length if we used padding. */
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+ if (padding) {
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+ if (ftruncate(fd,content_size) == -1) {
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+ /* Non critical error... */
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+ }
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}
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cleanup:
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+ sdsfree(content_padded);
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close(fd);
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- if (retval) unlink(tmp_conffile);
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return retval;
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}
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