fish: Allows win:... paths to work with drives mounted anywhere.

This allows you to mount disks on (eg) /c and /e and have the
guestfish win:... path mechanism map drive letters to the
right places.

3 files changed, 106 insertions, 86 deletions

diff --git a/TODO b/TODO
index b0cade9c..90238ca4 100644
--- a/TODO
+++ b/TODO
@@ -431,7 +431,3 @@ guestfish drive letters
 
 There should be an option to mount all Windows drives as separate
 paths, like C: => /c/, D: => /d/ etc.
-
-Also the code which detects if a drive letter is already mounted
-should be smarter: it should be able to detect if the drive is mounted
-on any path (not just /) and rewrite the path accordingly.
diff --git a/fish/fish.c b/fish/fish.c
index 1419c895..d6fed369 100644
--- a/fish/fish.c
+++ b/fish/fish.c
@@ -1376,10 +1376,13 @@ xwrite (int fd, const void *v_buf, size_t len)
 }
 
 /* Resolve the special "win:..." form for Windows-specific paths.  The
- * generated code calls this for all device or path arguments.  The
- * function must return a newly allocated string (caller frees) or
- * display an error and return NULL.
+ * generated code calls this for all device or path arguments.
+ *
+ * The function returns a newly allocated string, and the caller must
+ * free this string; else display an error and return NULL.
  */
+static char *win_prefix_drive_letter (char drive_letter, const char *path);
+
 char *
 win_prefix (const char *path)
 {
@@ -1396,97 +1399,113 @@ win_prefix (const char *path)
 
   path += 4;
 
-  /* Is there a drive letter? */
+  /* If there is a drive letter, rewrite the path. */
   if (c_isalpha (path[0]) && path[1] == ':') {
-    char drive_letter;
-    char **roots, **drives, **mountpoints, *device;
-    size_t i;
-
-    drive_letter = c_tolower (path[0]);
-    path += 2;
-
-    /* Resolve the drive letter using the drive mappings table. */
-    roots = guestfs_inspect_get_roots (g);
-    if (roots == NULL)
+    char drive_letter = c_tolower (path[0]);
+    /* This returns the newly allocated string. */
+    ret = win_prefix_drive_letter (drive_letter, path + 2);
+    if (ret == NULL)
       return NULL;
-    if (roots[0] == NULL) {
-      fprintf (stderr, _("%s: to use Windows drive letters, you must inspect the guest (\"-i\" option or run \"inspect-os\" command)\n"),
-               program_name);
-      free_strings (roots);
+  }
+  else if (!*path) {
+    ret = strdup ("/");
+    if (ret == NULL) {
+      perror ("strdup");
       return NULL;
     }
-    drives = guestfs_inspect_get_drive_mappings (g, roots[0]);
-    if (drives == NULL || drives[0] == NULL) {
-      fprintf (stderr, _("%s: to use Windows drive letters, this must be a Windows guest\n"),
-               program_name);
-      free_strings (roots);
-      free_strings (drives);
+  }
+  else {
+    ret = strdup (path);
+    if (ret == NULL) {
+      perror ("strdup");
       return NULL;
     }
+  }
 
-    device = NULL;
-    for (i = 0; drives[i] != NULL; i += 2) {
-      if (c_tolower (drives[i][0]) == drive_letter && drives[i][1] == '\0') {
-        device = drives[i+1];
-        break;
-      }
-    }
+  /* Blindly convert any backslashes into forward slashes.  Is this good? */
+  for (i = 0; i < strlen (ret); ++i)
+    if (ret[i] == '\\')
+      ret[i] = '/';
 
-    if (device == NULL) {
-      fprintf (stderr, _("%s: drive '%c:' not found.  To list available drives do:\n  inspect-get-drive-mappings %s\n"),
-               program_name, drive_letter, roots[0]);
-      free_strings (roots);
-      free_strings (drives);
-      return NULL;
-    }
+  char *t = guestfs_case_sensitive_path (g, ret);
+  free (ret);
+  ret = t;
 
-    /* This drive letter must be mounted on / (we won't do it). */
-    mountpoints = guestfs_mountpoints (g);
-    if (mountpoints == NULL) {
-      free_strings (roots);
-      free_strings (drives);
-      return NULL;
-    }
+  return ret;
+}
 
-    for (i = 0; mountpoints[i] != NULL; i += 2) {
-      if (STREQ (mountpoints[i+1], "/")) {
-        if (STRNEQ (mountpoints[i], device)) {
-          fprintf (stderr, _("%s: to access '%c:', mount %s on / first.  One way to do this is:\n  umount-all\n  mount %s /\n"),
-                   program_name, drive_letter, device, device);
-          free_strings (roots);
-          free_strings (drives);
-          free_strings (mountpoints);
-          return NULL;
-        }
-      }
+static char *
+win_prefix_drive_letter (char drive_letter, const char *path)
+{
+  char **roots = NULL;
+  char **drives = NULL;
+  char **mountpoints = NULL;
+  char *device, *mountpoint, *ret = NULL;
+  size_t i;
+
+  /* Resolve the drive letter using the drive mappings table. */
+  roots = guestfs_inspect_get_roots (g);
+  if (roots == NULL)
+    goto out;
+  if (roots[0] == NULL) {
+    fprintf (stderr, _("%s: to use Windows drive letters, you must inspect the guest (\"-i\" option or run \"inspect-os\" command)\n"),
+             program_name);
+    goto out;
+  }
+  drives = guestfs_inspect_get_drive_mappings (g, roots[0]);
+  if (drives == NULL || drives[0] == NULL) {
+    fprintf (stderr, _("%s: to use Windows drive letters, this must be a Windows guest\n"),
+             program_name);
+    goto out;
+  }
+
+  device = NULL;
+  for (i = 0; drives[i] != NULL; i += 2) {
+    if (c_tolower (drives[i][0]) == drive_letter && drives[i][1] == '\0') {
+      device = drives[i+1];
+      break;
     }
+  }
 
-    free_strings (roots);
-    free_strings (drives);
-    free_strings (mountpoints);
+  if (device == NULL) {
+    fprintf (stderr, _("%s: drive '%c:' not found.  To list available drives do:\n  inspect-get-drive-mappings %s\n"),
+             program_name, drive_letter, roots[0]);
+    goto out;
   }
 
-  if (!*path) {
-    ret = strdup ("/");
-    if (ret == NULL)
-      perror ("strdup");
-    return ret;
+  /* This drive letter must be mounted somewhere (we won't do it). */
+  mountpoints = guestfs_mountpoints (g);
+  if (mountpoints == NULL)
+    goto out;
+
+  mountpoint = NULL;
+  for (i = 0; mountpoints[i] != NULL; i += 2) {
+    if (STREQ (mountpoints[i], device)) {
+      mountpoint = mountpoints[i+1];
+      break;
+    }
   }
 
-  ret = strdup (path);
-  if (ret == NULL) {
-    perror ("strdup");
-    return NULL;
+  if (mountpoint == NULL) {
+    fprintf (stderr, _("%s: to access '%c:', mount %s first.  One way to do this is:\n  umount-all\n  mount %s /\n"),
+             program_name, drive_letter, device, device);
+    goto out;
   }
 
-  /* Blindly convert any backslashes into forward slashes.  Is this good? */
-  for (i = 0; i < strlen (ret); ++i)
-    if (ret[i] == '\\')
-      ret[i] = '/';
+  /* Rewrite the path, eg. if C: => /c then C:/foo => /c/foo */
+  if (asprintf (&ret, "%s%s%s",
+                mountpoint, STRNEQ (mountpoint, "/") ? "/" : "", path) == -1) {
+    perror ("asprintf");
+    goto out;
+  }
 
-  char *t = guestfs_case_sensitive_path (g, ret);
-  free (ret);
-  ret = t;
+ out:
+  if (roots)
+    free_strings (roots);
+  if (drives)
+    free_strings (drives);
+  if (mountpoints)
+    free_strings (mountpoints);
 
   return ret;
 }
diff --git a/fish/guestfish.pod b/fish/guestfish.pod
index 58f0bd9d..eb9ff39a 100644
--- a/fish/guestfish.pod
+++ b/fish/guestfish.pod
@@ -798,19 +798,24 @@ on each one.  Then you can close the mapper device:
 =head1 WINDOWS PATHS
 
 If a path is prefixed with C<win:> then you can use Windows-style
-paths (with some limitations).  The following commands are equivalent:
+drive letters and paths (with some limitations).  The following
+commands are equivalent:
 
  file /WINDOWS/system32/config/system.LOG
 
- file win:/windows/system32/config/system.log
-
  file win:\windows\system32\config\system.log
 
- file WIN:C:\Windows\SYSTEM32\conFIG\SYSTEM.LOG
+ file WIN:C:\Windows\SYSTEM32\CONFIG\SYSTEM.LOG
+
+The parameter is rewritten "behind the scenes" by looking up the
+position where the drive is mounted, prepending that to the path,
+changing all backslash characters to forward slash, then resolving the
+result using L</case-sensitive-path>.  For example if the E: drive
+was mounted on C</e> then the parameter might be rewritten like this:
+
+ win:e:\foo\bar => /e/FOO/bar
 
-This syntax implicitly calls C<case-sensitive-path> (q.v.) so it also
-handles case insensitivity like Windows would.  This only works in
-argument positions that expect a path.
+This only works in argument positions that expect a path.
 
 =head1 UPLOADING AND DOWNLOADING FILES