ip vrf: Refactor ipvrf_identify

Split ipvrf_identify into arg processing and a function that does the
actual cgroup file parsing. The latter function is used in a follow
on patch.

In the process, convert the reading of the cgroups file to use fopen
and fgets just in case the file ever grows beyond 4k. Move printing
of any error message and the vrf name to the caller of the new
vrf_identify.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>

diff --git a/ip/ipvrf.c b/ip/ipvrf.c
index 44ad7e07024acea0a3041d9b623086cee8e5acb8..a2669f339691b995bbce59dbde97351db4506f89 100644 (file)
--- a/ip/ipvrf.c
+++ b/ip/ipvrf.c
@@ -40,14 +40,43 @@ static void usage(void)
        exit(-1);
 }
 
-static int ipvrf_identify(int argc, char **argv)
+static int vrf_identify(pid_t pid, char *name, size_t len)
 {
        char path[PATH_MAX];
        char buf[4096];
        char *vrf, *end;
-       int fd, rc = -1;
+       FILE *fp;
+
+       snprintf(path, sizeof(path), "/proc/%d/cgroup", pid);
+       fp = fopen(path, "r");
+       if (!fp)
+               return -1;
+
+       memset(name, 0, len);
+
+       while (fgets(buf, sizeof(buf), fp)) {
+               vrf = strstr(buf, "::/vrf/");
+               if (vrf) {
+                       vrf += 7;  /* skip past "::/vrf/" */
+                       end = strchr(vrf, '\n');
+                       if (end)
+                               *end = '\0';
+
+                       strncpy(name, vrf, len - 1);
+                       break;
+               }
+       }
+
+       fclose(fp);
+
+       return 0;
+}
+
+static int ipvrf_identify(int argc, char **argv)
+{
+       char vrf[32];
+       int rc;
        unsigned int pid;
-       ssize_t n;
 
        if (argc < 1)
                pid = getpid();
@@ -56,35 +85,15 @@ static int ipvrf_identify(int argc, char **argv)
        else if (get_unsigned(&pid, argv[0], 10))
                invarg("Invalid pid\n", argv[0]);
 
-       snprintf(path, sizeof(path), "/proc/%d/cgroup", pid);
-       fd = open(path, O_RDONLY);
-       if (fd < 0) {
-               fprintf(stderr,
-                       "Failed to open cgroups file: %s\n", strerror(errno));
-               return -1;
-       }
-
-       n = read(fd, buf, sizeof(buf) - 1);
-       if (n < 0) {
-               fprintf(stderr,
-                       "Failed to read cgroups file: %s\n", strerror(errno));
-               goto out;
-       }
-       buf[n] = '\0';
-       vrf = strstr(buf, "::/vrf/");
-       if (vrf) {
-               vrf += 7;  /* skip past "::/vrf/" */
-               end = strchr(vrf, '\n');
-               if (end)
-                       *end = '\0';
-
-               printf("%s\n", vrf);
+       rc = vrf_identify(pid, vrf, sizeof(vrf));
+       if (!rc) {
+               if (vrf[0] != '\0')
+                       printf("%s\n", vrf);
+       } else {
+               fprintf(stderr, "Failed to lookup vrf association: %s\n",
+                       strerror(errno));
        }
 
-       rc = 0;
-out:
-       close(fd);
-
        return rc;
 }