Rewrite an invalid config file

We saw a case of config file being corrupted. Add a mechanism to
recover from this when wifi is toggled off and on.

Bug: 8569820
Change-Id: If2baceb065838d2adb5cde61772d25a05455fc90

1 files changed, 35 insertions, 26 deletions

diff --git a/wifi/wifi.c b/wifi/wifi.c
index b0ef345..30933fe 100644
--- a/wifi/wifi.c
+++ b/wifi/wifi.c
@@ -342,6 +342,7 @@ int update_ctrl_interface(const char *config_file) {
     char *pbuf;
     char *sptr;
     struct stat sb;
+    int ret;
 
     if (stat(config_file, &sb) != 0)
         return -1;
@@ -368,6 +369,8 @@ int update_ctrl_interface(const char *config_file) {
     } else {
         strcpy(ifc, CONTROL_IFACE_PATH);
     }
+    /* Assume file is invalid to begin with */
+    ret = -1;
     /*
      * if there is a "ctrl_interface=<value>" entry, re-write it ONLY if it is
      * NOT a directory.  The non-directory value option is an Android add-on
@@ -378,33 +381,35 @@ int update_ctrl_interface(const char *config_file) {
      * The <value> is deemed to be a directory if the "DIR=" form is used or
      * the value begins with "/".
      */
-    if ((sptr = strstr(pbuf, "ctrl_interface=")) &&
-        (!strstr(pbuf, "ctrl_interface=DIR=")) &&
-        (!strstr(pbuf, "ctrl_interface=/"))) {
-        char *iptr = sptr + strlen("ctrl_interface=");
-        int ilen = 0;
-        int mlen = strlen(ifc);
-        int nwrite;
-        if (strncmp(ifc, iptr, mlen) != 0) {
-            ALOGE("ctrl_interface != %s", ifc);
-            while (((ilen + (iptr - pbuf)) < nread) && (iptr[ilen] != '\n'))
-                ilen++;
-            mlen = ((ilen >= mlen) ? ilen : mlen) + 1;
-            memmove(iptr + mlen, iptr + ilen + 1, nread - (iptr + ilen + 1 - pbuf));
-            memset(iptr, '\n', mlen);
-            memcpy(iptr, ifc, strlen(ifc));
-            destfd = TEMP_FAILURE_RETRY(open(config_file, O_RDWR, 0660));
-            if (destfd < 0) {
-                ALOGE("Cannot update \"%s\": %s", config_file, strerror(errno));
-                free(pbuf);
-                return -1;
+    if (sptr = strstr(pbuf, "ctrl_interface=")) {
+        ret = 0;
+        if ((!strstr(pbuf, "ctrl_interface=DIR=")) &&
+                (!strstr(pbuf, "ctrl_interface=/"))) {
+            char *iptr = sptr + strlen("ctrl_interface=");
+            int ilen = 0;
+            int mlen = strlen(ifc);
+            int nwrite;
+            if (strncmp(ifc, iptr, mlen) != 0) {
+                ALOGE("ctrl_interface != %s", ifc);
+                while (((ilen + (iptr - pbuf)) < nread) && (iptr[ilen] != '\n'))
+                    ilen++;
+                mlen = ((ilen >= mlen) ? ilen : mlen) + 1;
+                memmove(iptr + mlen, iptr + ilen + 1, nread - (iptr + ilen + 1 - pbuf));
+                memset(iptr, '\n', mlen);
+                memcpy(iptr, ifc, strlen(ifc));
+                destfd = TEMP_FAILURE_RETRY(open(config_file, O_RDWR, 0660));
+                if (destfd < 0) {
+                    ALOGE("Cannot update \"%s\": %s", config_file, strerror(errno));
+                    free(pbuf);
+                    return -1;
+                }
+                TEMP_FAILURE_RETRY(write(destfd, pbuf, nread + mlen - ilen -1));
+                close(destfd);
             }
-            TEMP_FAILURE_RETRY(write(destfd, pbuf, nread + mlen - ilen -1));
-            close(destfd);
         }
     }
     free(pbuf);
-    return 0;
+    return ret;
 }
 
 int ensure_config_file_exists(const char *config_file)
@@ -422,9 +427,13 @@ int ensure_config_file_exists(const char *config_file)
             ALOGE("Cannot set RW to \"%s\": %s", config_file, strerror(errno));
             return -1;
         }
-        /* return if filesize is at least 10 bytes */
-        if (stat(config_file, &sb) == 0 && sb.st_size > 10) {
-            return update_ctrl_interface(config_file);
+        /* return if we were able to update control interface properly */
+        if (update_ctrl_interface(config_file) >=0) {
+            return 0;
+        } else {
+            /* This handles the scenario where the file had bad data
+             * for some reason. We continue and recreate the file.
+             */
         }
     } else if (errno != ENOENT) {
         ALOGE("Cannot access \"%s\": %s", config_file, strerror(errno));