diff -up nfs-utils-2.3.3/support/nfs/conffile.c.orig nfs-utils-2.3.3/support/nfs/conffile.c
--- nfs-utils-2.3.3/support/nfs/conffile.c.orig 2018-09-06 14:09:08.000000000 -0400
+++ nfs-utils-2.3.3/support/nfs/conffile.c 2019-04-25 10:58:27.199907596 -0400
@@ -50,6 +50,7 @@
#include <err.h>
#include <syslog.h>
#include <libgen.h>
+#include <sys/file.h>
#include "conffile.h"
#include "xlog.h"
@@ -509,6 +510,17 @@ conf_readfile(const char *path)
return NULL;
}
+ /* Grab a shared lock to ensure its not mid-rewrite */
+ if (flock(fd, LOCK_SH)) {
+ xlog_warn("conf_readfile: attempt to grab read lock failed: %s",
+ strerror(errno));
+ goto fail;
+ }
+
+ /* only after we have the lock, check the file size ready to read it */
+ sz = lseek(fd, 0, SEEK_END);
+ lseek(fd, 0, SEEK_SET);
+
new_conf_addr = malloc(sz+1);
if (!new_conf_addr) {
xlog_warn("conf_readfile: malloc (%lu) failed", (unsigned long)sz);
@@ -1588,6 +1600,17 @@ flush_outqueue(struct tailhead *queue, F
return 0;
}
+/* append one queue to another */
+static void
+append_queue(struct tailhead *inq, struct tailhead *outq)
+{
+ while (inq->tqh_first != NULL) {
+ struct outbuffer *ob = inq->tqh_first;
+ TAILQ_REMOVE(inq, ob, link);
+ TAILQ_INSERT_TAIL(outq, ob, link);
+ }
+}
+
/* read one line of text from a file, growing the buffer as necessary */
static int
read_line(char **buff, int *buffsize, FILE *in)
@@ -1728,6 +1751,16 @@ is_folded(const char *line)
return false;
}
+static int
+lock_file(FILE *f)
+{
+ int ret;
+ ret = flock(fileno(f), LOCK_EX);
+ if (ret)
+ xlog(L_ERROR, "Error could not lock the file");
+ return ret;
+}
+
/***
* Write a value to an nfs.conf style filename
*
@@ -1738,15 +1771,14 @@ int
conf_write(const char *filename, const char *section, const char *arg,
const char *tag, const char *value)
{
- int fdout = -1;
- char *outpath = NULL;
- FILE *outfile = NULL;
FILE *infile = NULL;
int ret = 1;
struct tailhead outqueue;
+ struct tailhead inqueue;
char * buff = NULL;
int buffsize = 0;
+ TAILQ_INIT(&inqueue);
TAILQ_INIT(&outqueue);
if (!filename) {
@@ -1759,26 +1791,7 @@ conf_write(const char *filename, const c
return ret;
}
- if (asprintf(&outpath, "%s.XXXXXX", filename) == -1) {
- xlog(L_ERROR, "conf_write: error composing temp filename");
- return ret;
- }
-
- fdout = mkstemp(outpath);
- if (fdout < 0) {
- xlog(L_ERROR, "conf_write: open temp file %s failed: %s",
- outpath, strerror(errno));
- goto cleanup;
- }
-
- outfile = fdopen(fdout, "w");
- if (!outfile) {
- xlog(L_ERROR, "conf_write: fdopen temp file failed: %s",
- strerror(errno));
- goto cleanup;
- }
-
- infile = fopen(filename, "r");
+ infile = fopen(filename, "r+");
if (!infile) {
if (!value) {
xlog_warn("conf_write: config file \"%s\" not found, nothing to do", filename);
@@ -1787,18 +1800,29 @@ conf_write(const char *filename, const c
}
xlog_warn("conf_write: config file \"%s\" not found, creating.", filename);
- if (append_line(&outqueue, NULL, make_section(section, arg)))
+ infile = fopen(filename, "wx");
+ if (!infile) {
+ xlog(L_ERROR, "conf_write: Error creating config file \"%s\".", filename);
+ goto cleanup;
+ }
+
+ if (lock_file(infile))
goto cleanup;
- if (append_line(&outqueue, NULL, make_tagline(tag, value)))
+ if (append_line(&inqueue, NULL, make_section(section, arg)))
goto cleanup;
- if (flush_outqueue(&outqueue, outfile))
+ if (append_line(&inqueue, NULL, make_tagline(tag, value)))
goto cleanup;
+
+ append_queue(&inqueue, &outqueue);
} else {
bool found = false;
int err = 0;
+ if (lock_file(infile))
+ goto cleanup;
+
buffsize = 4096;
buff = calloc(1, buffsize);
if (buff == NULL) {
@@ -1813,7 +1837,7 @@ conf_write(const char *filename, const c
/* read in one section worth of lines */
do {
if (*buff != '\0') {
- if (append_line(&outqueue, NULL, strdup(buff)))
+ if (append_line(&inqueue, NULL, strdup(buff)))
goto cleanup;
}
@@ -1821,7 +1845,7 @@ conf_write(const char *filename, const c
} while (err == 0 && buff[0] != '[');
/* find the section header */
- where = TAILQ_FIRST(&outqueue);
+ where = TAILQ_FIRST(&inqueue);
while (where != NULL) {
if (where->text != NULL && where->text[0] == '[')
break;
@@ -1845,7 +1869,7 @@ conf_write(const char *filename, const c
/* remove current tag */
do {
struct outbuffer *next = TAILQ_NEXT(where, link);
- TAILQ_REMOVE(&outqueue, where, link);
+ TAILQ_REMOVE(&inqueue, where, link);
if (is_folded(where->text))
again = true;
else
@@ -1857,14 +1881,14 @@ conf_write(const char *filename, const c
/* insert new tag */
if (value) {
- if (append_line(&outqueue, prev, make_tagline(tag, value)))
+ if (append_line(&inqueue, prev, make_tagline(tag, value)))
goto cleanup;
}
} else
/* no existing assignment found and we need to add one */
if (value) {
/* rewind past blank lines and comments */
- struct outbuffer *tail = TAILQ_LAST(&outqueue, tailhead);
+ struct outbuffer *tail = TAILQ_LAST(&inqueue, tailhead);
/* comments immediately before a section usually relate
* to the section below them */
@@ -1876,7 +1900,7 @@ conf_write(const char *filename, const c
tail = TAILQ_PREV(tail, tailhead, link);
/* now add the tag here */
- if (append_line(&outqueue, tail, make_tagline(tag, value)))
+ if (append_line(&inqueue, tail, make_tagline(tag, value)))
goto cleanup;
found = true;
@@ -1886,49 +1910,45 @@ conf_write(const char *filename, const c
/* EOF and correct section not found, so add one */
if (err && !found && value) {
/* did the last section end in a blank line */
- struct outbuffer *tail = TAILQ_LAST(&outqueue, tailhead);
+ struct outbuffer *tail = TAILQ_LAST(&inqueue, tailhead);
if (tail && !is_empty(tail->text)) {
/* no, so add one for clarity */
- if (append_line(&outqueue, NULL, strdup("\n")))
+ if (append_line(&inqueue, NULL, strdup("\n")))
goto cleanup;
}
/* add the new section header */
- if (append_line(&outqueue, NULL, make_section(section, arg)))
+ if (append_line(&inqueue, NULL, make_section(section, arg)))
goto cleanup;
/* now add the tag */
- if (append_line(&outqueue, NULL, make_tagline(tag, value)))
+ if (append_line(&inqueue, NULL, make_tagline(tag, value)))
goto cleanup;
}
- /* we are done with this section, write it out */
- if (flush_outqueue(&outqueue, outfile))
- goto cleanup;
+ /* we are done with this section, move it to the out queue */
+ append_queue(&inqueue, &outqueue);
} while(err == 0);
}
- if (infile) {
- fclose(infile);
- infile = NULL;
- }
+ /* now rewind and overwrite the file with the updated data */
+ rewind(infile);
- fdout = -1;
- if (fclose(outfile)) {
- xlog(L_ERROR, "Error writing config file: %s", strerror(errno));
+ if (ftruncate(fileno(infile), 0)) {
+ xlog(L_ERROR, "Error truncating config file");
goto cleanup;
}
- /* now swap the old file for the new one */
- if (rename(outpath, filename)) {
- xlog(L_ERROR, "Error updating config file: %s: %s\n", filename, strerror(errno));
- ret = 1;
- } else {
- ret = 0;
- free(outpath);
- outpath = NULL;
+ if (flush_outqueue(&outqueue, infile))
+ goto cleanup;
+
+ if (infile) {
+ fclose(infile);
+ infile = NULL;
}
+ ret = 0;
+
cleanup:
flush_outqueue(&outqueue, NULL);
@@ -1936,11 +1956,5 @@ cleanup:
free(buff);
if (infile)
fclose(infile);
- if (fdout != -1)
- close(fdout);
- if (outpath) {
- unlink(outpath);
- free(outpath);
- }
return ret;
}