[Libguestfs] [PATCH 08/10] info: Use command mini-library to run 'qemu-img info' commands.
Richard W.M. Jones
rjones at redhat.com
Thu Oct 18 21:14:09 UTC 2012
From: "Richard W.M. Jones" <rjones at redhat.com>
---
src/info.c | 224 +++++++++++++++++++++++++------------------------------------
1 file changed, 91 insertions(+), 133 deletions(-)
diff --git a/src/info.c b/src/info.c
index 958f7b0..156c11f 100644
--- a/src/info.c
+++ b/src/info.c
@@ -33,124 +33,142 @@
#include "guestfs-internal-actions.h"
#include "guestfs_protocol.h"
-static int run_qemu_img_info (guestfs_h *g, const char *filename, int (*fn) (guestfs_h *g, char *line, void *data), void *data);
-static int check_disk_format (guestfs_h *h, char *line, void *data);
-static int check_disk_virtual_size (guestfs_h *h, char *line, void *data);
-static int check_disk_has_backing_file (guestfs_h *h, char *line, void *data);
+static int run_qemu_img_info (guestfs_h *g, const char *filename, cmd_stdout_callback cb, void *data);
+
+/* NB: For security reasons, the check_* callbacks MUST bail
+ * after seeing the first line that matches /^backing file: /. See:
+ * https://lists.gnu.org/archive/html/qemu-devel/2012-09/msg00137.html
+ * Eventually we should use the JSON output of qemu-img info.
+ */
+
+struct check_data {
+ int stop, failed;
+ union {
+ char *ret;
+ int reti;
+ int64_t reti64;
+ };
+};
+
+static void check_disk_format (guestfs_h *g, void *data, const char *line, size_t len);
+static void check_disk_virtual_size (guestfs_h *g, void *data, const char *line, size_t len);
+static void check_disk_has_backing_file (guestfs_h *g, void *data, const char *line, size_t len);
char *
guestfs__disk_format (guestfs_h *g, const char *filename)
{
- char *ret = NULL;
+ struct check_data data;
+
+ memset (&data, 0, sizeof data);
- if (run_qemu_img_info (g, filename, check_disk_format, &ret) == -1) {
- free (ret);
+ if (run_qemu_img_info (g, filename, check_disk_format, &data) == -1) {
+ free (data.ret);
return NULL;
}
- if (ret == NULL)
- ret = safe_strdup (g, "unknown");
+ if (data.ret == NULL)
+ data.ret = safe_strdup (g, "unknown");
- return ret;
+ return data.ret;
}
-static int
-check_disk_format (guestfs_h *g, char *line, void *retpv)
+static void
+check_disk_format (guestfs_h *g, void *datav, const char *line, size_t len)
{
- char **retp = retpv;
- char *p;
- size_t n;
+ struct check_data *data = datav;
+ const char *p;
+
+ if (data->stop)
+ return;
+
+ if (STRPREFIX (line, "backing file: ")) {
+ data->stop = 1;
+ return;
+ }
if (STRPREFIX (line, "file format: ")) {
p = &line[13];
- n = strlen (p);
- if (n > 0 && p[n-1] == '\n')
- p[n-1] = '\0';
- *retp = safe_strdup (g, p);
- return 0; /* finish processing */
+ data->ret = safe_strdup (g, p);
+ data->stop = 1;
}
-
- return 1; /* continue processing */
}
int64_t
guestfs__disk_virtual_size (guestfs_h *g, const char *filename)
{
- int64_t ret = -1;
+ struct check_data data;
- if (run_qemu_img_info (g, filename, check_disk_virtual_size, &ret) == -1)
+ memset (&data, 0, sizeof data);
+
+ if (run_qemu_img_info (g, filename, check_disk_virtual_size, &data) == -1)
return -1;
- if (ret == -1)
+ if (data.failed)
error (g, _("%s: cannot detect virtual size of disk image"), filename);
- return ret;
+ return data.reti64;
}
-static int
-check_disk_virtual_size (guestfs_h *g, char *line, void *retpv)
+static void
+check_disk_virtual_size (guestfs_h *g, void *datav,
+ const char *line, size_t len)
{
- int64_t *retp = retpv;
- char *p;
+ struct check_data *data = datav;
+ const char *p;
+
+ if (data->stop)
+ return;
+
+ if (STRPREFIX (line, "backing file: ")) {
+ data->stop = 1;
+ return;
+ }
if (STRPREFIX (line, "virtual size: ")) {
/* "virtual size: 500M (524288000 bytes)\n" */
p = &line[14];
p = strchr (p, ' ');
- if (!p || p[1] != '(' || sscanf (&p[2], "%" SCNi64, retp) != 1) {
- error (g, _("cannot parse output of qemu-img info: '%s'"),
- line);
- return -1;
- }
- return 0; /* finish processing */
+ if (!p || p[1] != '(' || sscanf (&p[2], "%" SCNi64, &data->reti64) != 1)
+ data->failed = 1;
+ data->stop = 1;
}
-
- return 1; /* continue processing */
}
int
guestfs__disk_has_backing_file (guestfs_h *g, const char *filename)
{
- int ret = 0;
+ struct check_data data;
+
+ memset (&data, 0, sizeof data);
- if (run_qemu_img_info (g, filename, check_disk_has_backing_file, &ret) == -1)
+ if (run_qemu_img_info (g, filename, check_disk_has_backing_file, &data) == -1)
return -1;
- return ret;
+ return data.reti;
}
-static int
-check_disk_has_backing_file (guestfs_h *g, char *line, void *retpv)
+static void
+check_disk_has_backing_file (guestfs_h *g, void *datav,
+ const char *line, size_t len)
{
- int *retp = retpv;
+ struct check_data *data = datav;
+
+ if (data->stop)
+ return;
if (STRPREFIX (line, "backing file: ")) {
- *retp = 1;
- return 0; /* finish processing */
+ data->reti = 1;
+ data->stop = 1;
}
-
- return 1; /* continue processing */
}
-/* It's hard to use 'qemu-img info' safely. See:
- * https://lists.gnu.org/archive/html/qemu-devel/2012-09/msg00137.html
- * Eventually we should switch to the JSON output format, when it
- * becomes available. In the meantime: (1) make a symlink to ensure
- * we control the input filename, and (2) bail parsing as soon as
- * /^backing file: / is seen in the input.
- */
static int
run_qemu_img_info (guestfs_h *g, const char *filename,
- int (*fn) (guestfs_h *g, char *line, void *data),
- void *data)
+ cmd_stdout_callback fn, void *data)
{
char *abs_filename = NULL;
char *safe_filename = NULL;
- pid_t pid = 0;
- int fd[2] = { -1, -1 };
- FILE *fp = NULL;
- char *line = NULL;
- size_t len;
+ struct command *cmd = NULL;
int r;
if (guestfs___lazy_make_tmpdir (g) == -1)
@@ -170,90 +188,30 @@ run_qemu_img_info (guestfs_h *g, const char *filename,
goto error;
}
- if (pipe2 (fd, O_CLOEXEC) == -1) {
- perrorf (g, "pipe2");
- goto error;
- }
-
- pid = fork ();
- if (pid == -1) {
- perrorf (g, "fork");
+ cmd = guestfs___new_command (g);
+ guestfs___cmd_add_arg (cmd, "qemu-img");
+ guestfs___cmd_add_arg (cmd, "info");
+ guestfs___cmd_add_arg (cmd, safe_filename);
+ guestfs___cmd_set_stdout_callback (cmd, fn, data, 0);
+ r = guestfs___cmd_run (cmd);
+ if (r == -1)
goto error;
- }
-
- if (pid == 0) { /* child */
- close (fd[0]);
- dup2 (fd[1], 1);
- close (fd[1]);
-
- setenv ("LC_ALL", "C", 1);
-
- /* XXX stderr to event log */
-
- execlp ("qemu-img", "qemu-img", "info", safe_filename, NULL);
- perror ("could not execute 'qemu-img info' command");
- _exit (EXIT_FAILURE);
- }
-
- close (fd[1]);
- fd[1] = -1;
-
- fp = fdopen (fd[0], "r");
- if (fp == NULL) {
- perrorf (g, "fdopen: qemu-img info");
- goto error;
- }
- fd[0] = -1;
-
- while (getline (&line, &len, fp) != -1) {
- r = fn (g, line, data);
- if (r == -1) /* error */
- goto error;
- if (r == 0) /* finished processing */
- break;
-
- /* This is for security reasons, see comment above. */
- if (STRPREFIX (line, "backing file: "))
- break;
- }
-
- if (fclose (fp) == -1) { /* also closes fd[0] */
- perrorf (g, "fclose");
- fp = NULL;
- goto error;
- }
- fp = NULL;
-
- if (waitpid (pid, &r, 0) == -1) {
- perrorf (g, "waitpid");
- pid = 0;
- goto error;
- }
- pid = 0;
-
if (!WIFEXITED (r) || WEXITSTATUS (r) != 0) {
- error (g, "qemu-img: %s: child process failed", filename);
+ error (g, _("qemu-img: %s: child process failed"), filename);
goto error;
}
+ guestfs___cmd_close (cmd);
free (safe_filename);
free (abs_filename);
- free (line);
return 0;
error:
- if (fd[0] >= 0)
- close (fd[0]);
- if (fd[1] >= 0)
- close (fd[1]);
- if (fp != NULL)
- fclose (fp);
- if (pid > 0)
- waitpid (pid, NULL, 0);
+ if (cmd)
+ guestfs___cmd_close (cmd);
free (safe_filename);
free (abs_filename);
- free (line);
return -1;
}
--
1.7.11.4
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