VFS: Respect -C flag

VFS feature uses the same -C flag as the overlays system.
jart · Mar 8, 2023 · a97a8dc · a97a8dc
1 parent 0cc2b6c
commit a97a8dc
Show file tree

Hide file tree

Showing 6 changed files with 30 additions and 9 deletions.
diff --git a/blink/blink.c b/blink/blink.c
@@ -112,7 +112,7 @@ _Alignas(1) static const char USAGE[] =
     "  -Z                   print internal statistics on exit\n"
     "  -L PATH              log filename (default is blink.log)\n"
 #endif
-#ifndef DISABLE_OVERLAYS
+#if !defined(DISABLE_OVERLAYS) || !defined(DISABLE_VFS)
     "  -C PATH              sets chroot dir or overlay spec [default \":o\"]\n"
 #endif
 #if !defined(DISABLE_OVERLAYS) || !defined(NDEBUG)
@@ -121,6 +121,9 @@ _Alignas(1) static const char USAGE[] =
 #ifndef DISABLE_OVERLAYS
     "  $BLINK_OVERLAYS      file system roots [default \":o\"]\n"
 #endif
+#ifndef DISABLE_VFS
+    "  $BLINK_PREFIX        file system root [default \"/\"]\n"
+#endif
 #ifndef NDEBUG
 
     "  $BLINK_LOG_FILENAME  log filename (same as -L flag)\n"
@@ -256,6 +259,9 @@ static void GetOpts(int argc, char *argv[]) {
   FLAG_overlays = getenv("BLINK_OVERLAYS");
   if (!FLAG_overlays) FLAG_overlays = DEFAULT_OVERLAYS;
 #endif
+#ifndef DISABLE_VFS
+  FLAG_prefix = getenv("BLINK_PREFIX");
+#endif
 #if LOG_ENABLED
   FLAG_logpath = getenv("BLINK_LOG_FILENAME");
 #endif
@@ -289,10 +295,12 @@ static void GetOpts(int argc, char *argv[]) {
         FLAG_logpath = optarg_;
         break;
       case 'C':
-#ifndef DISABLE_OVERLAYS
+#if !defined(DISABLE_OVERLAYS)
         FLAG_overlays = optarg_;
+#elif !defined(DISABLE_VFS)
+        FLAG_prefix = optarg_;
 #else
-        WriteErrorString("error: overlays support was disabled\n");
+        WriteErrorString("error: overlays and vfs support were both disabled\n");
 #endif
         break;
       case 'v':
@@ -367,7 +375,7 @@ int main(int argc, char *argv[]) {
   }
 #endif
 #ifndef DISABLE_VFS
-  if (VfsInit()) {
+  if (VfsInit(FLAG_prefix)) {
     WriteErrorString("error: vfs initialization failed\n");
     exit(1);
   }

diff --git a/blink/blinkenlights.c b/blink/blinkenlights.c
@@ -3798,6 +3798,9 @@ static void GetOpts(int argc, char *argv[]) {
 #ifndef DISABLE_OVERLAYS
   FLAG_overlays = getenv("BLINK_OVERLAYS");
   if (!FLAG_overlays) FLAG_overlays = DEFAULT_OVERLAYS;
+#endif
+#ifndef DISABLE_VFS
+  FLAG_prefix = getenv("BLINK_PREFIX");
 #endif
   while ((opt = GetOpt(argc, argv, "0hjmvVtrzRNsZb:Hw:L:C:")) != -1) {
     switch (opt) {
@@ -3854,8 +3857,10 @@ static void GetOpts(int argc, char *argv[]) {
         FLAG_logpath = optarg_;
         break;
       case 'C':
-#ifndef DISABLE_OVERLAYS
+#if !defined(DISABLE_OVERLAYS)
         FLAG_overlays = optarg_;
+#elif !defined(DISABLE_VFS)
+        FLAG_prefix = optarg_;
 #else
         WriteErrorString("error: overlays support was disabled\n");
 #endif
@@ -4042,7 +4047,7 @@ int main(int argc, char *argv[]) {
   }
 #endif
 #ifndef DISABLE_VFS
-  if (VfsInit()) {
+  if (VfsInit(FLAG_prefix)) {
     WriteErrorString("error: vfs initialization failed\n");
     exit(1);
   }

diff --git a/blink/flag.c b/blink/flag.c
@@ -45,3 +45,6 @@ const char *FLAG_logpath;
 #ifndef DISABLE_OVERLAYS
 const char *FLAG_overlays;
 #endif
+#ifndef DISABLE_VFS
+const char *FLAG_prefix;
+#endif
diff --git a/blink/flag.h b/blink/flag.h
@@ -27,5 +27,6 @@ extern u64 FLAG_dyninterpaddr;
 
 extern const char *FLAG_logpath;
 extern const char *FLAG_overlays;
+extern const char *FLAG_prefix;
 
 #endif /* BLINK_FLAG_H_ */
diff --git a/blink/vfs.c b/blink/vfs.c
@@ -92,7 +92,7 @@ static struct Vfs g_vfs = {
     .mapslock = PTHREAD_MUTEX_INITIALIZER_,
 };
 
-int VfsInit(void) {
+int VfsInit(const char *prefix) {
   struct stat st;
   char *cwd, hostcwd[PATH_MAX], *bprefix = NULL;
   struct VfsInfo *info;
@@ -108,13 +108,17 @@ int VfsInit(void) {
 
   // Initialize the root directory
   unassert(!VfsAcquireInfo(&g_initialrootinfo, &g_rootinfo));
-  bprefix = realpath(getenv("BLINK_PREFIX"), NULL);
+  if (prefix) {
+    bprefix = realpath(prefix, NULL);
+  }
   if (bprefix) {
     if (stat(bprefix, &st) == -1) {
       ERRF("Failed to stat BLINK_PREFIX %s, %s", bprefix, strerror(errno));
+      free(bprefix);
       bprefix = NULL;
     } else if (!S_ISDIR(st.st_mode)) {
       ERRF("BLINK_PREFIX %s is not a directory", bprefix);
+      free(bprefix);
       bprefix = NULL;
     }
   }

diff --git a/blink/vfs.h b/blink/vfs.h
@@ -255,7 +255,7 @@ int VfsMunmap(void *, size_t);
 int VfsMprotect(void *, size_t, int);
 int VfsMsync(void *, size_t, int);
 
-int VfsInit(void);
+int VfsInit(const char *);
 int VfsRegister(struct VfsSystem *);
 int VfsTraverse(const char *, struct VfsInfo **, bool);
 int VfsCreateInfo(struct VfsInfo **);