7:27 a.m.
Use an extensible buffer (a vector<char>) when reading
/proc/self/cmdline.
Tidy up some error messages.
---
plugins/vddk/reexec.c | 57 ++++++++++++++++++++++++++-----------------
1 file changed, 35 insertions(+), 22 deletions(-)
diff --git a/plugins/vddk/reexec.c b/plugins/vddk/reexec.c
index 5a5e9844..9641ee8c 100644
--- a/plugins/vddk/reexec.c
+++ b/plugins/vddk/reexec.c
@@ -48,6 +48,19 @@
char *reexeced; /* orig LD_LIBRARY_PATH on reexec */
+/* Extensible buffer (string). */
+DEFINE_VECTOR_TYPE(buffer, char);
+
+#define CLEANUP_FREE_BUFFER \
+ __attribute__((cleanup (cleanup_free_buffer)))
+
+static void
+cleanup_free_buffer (buffer *v)
+{
+ free (v->ptr);
+}
+
+/* List of strings. */
DEFINE_VECTOR_TYPE(string_vector, char *);
#define CLEANUP_FREE_STRING_VECTOR \
@@ -68,11 +81,13 @@ cleanup_free_string_vector (string_vector *v)
static void
perform_reexec (const char *env, const char *prepend)
{
+ static const char cmdline_file[] = "/proc/self/cmdline";
+ static const char exe_file[] = "/proc/self/exe";
CLEANUP_FREE char *library = NULL;
+ CLEANUP_FREE_BUFFER buffer buf = empty_vector;
CLEANUP_FREE_STRING_VECTOR string_vector argv = empty_vector;
int fd;
- size_t len = 0, buflen = 512;
- CLEANUP_FREE char *buf = NULL;
+ size_t len;
/* In order to re-exec, we need our original command line. The
* Linux kernel does not make it easy to know in advance how large
@@ -80,42 +95,40 @@ perform_reexec (const char *env, const char *prepend)
* until we get a short read. This assumes nbdkit did not alter its
* original argv[].
*/
- fd = open ("/proc/self/cmdline", O_RDONLY);
+ fd = open (cmdline_file, O_RDONLY|O_CLOEXEC);
if (fd == -1) {
- nbdkit_debug ("failure to parse original argv: %m");
+ nbdkit_debug ("open: %s: %m", cmdline_file);
return;
}
- do {
- char *p = realloc (buf, buflen * 2);
+ for (;;) {
ssize_t r;
- if (!p) {
- nbdkit_debug ("failure to parse original argv: %m");
+ if (buffer_reserve (&buf, 512) == -1) {
+ nbdkit_debug ("realloc: %m");
return;
}
- buf = p;
- buflen *= 2;
- r = read (fd, buf + len, buflen - len);
+ r = read (fd, buf.ptr + buf.size, buf.alloc - buf.size);
if (r == -1) {
- nbdkit_debug ("failure to parse original argv: %m");
+ nbdkit_debug ("read: %s: %m", cmdline_file);
return;
}
- len += r;
- } while (len == buflen);
- nbdkit_debug ("original command line occupies %zu bytes", len);
+ if (r == 0)
+ break;
+ buf.size += r;
+ }
+ close (fd);
+ nbdkit_debug ("original command line occupies %zu bytes", buf.size);
/* Split cmdline into argv, then append one more arg. */
- buflen = len;
- len = 0;
- while (len < buflen) {
- if (string_vector_append (&argv, buf + len) == -1) {
+ for (len = 0; len < buf.size; len += strlen (buf.ptr + len) + 1) {
+ if (string_vector_append (&argv, buf.ptr + len) == -1) {
argv_realloc_fail:
nbdkit_debug ("argv: realloc: %m");
return;
}
- len += strlen (buf + len) + 1;
}
+
if (!env)
env = "";
nbdkit_debug ("adding reexeced_=%s", env);
@@ -139,8 +152,8 @@ perform_reexec (const char *env, const char *prepend)
nbdkit_debug ("re-executing with updated LD_LIBRARY_PATH=%s", library);
fflush (NULL);
- execvp ("/proc/self/exe", argv.ptr);
- nbdkit_debug ("failure to execvp: %m");
+ execvp (exe_file, argv.ptr);
+ nbdkit_debug ("execvp: %s: %m", exe_file);
}
/* See if prepend is already in LD_LIBRARY_PATH; if not, re-exec. */
--
2.25.0