[Qemu-devel] rev1 [PATCH] support colon in filenames

[Ram Pai]

Problem: It is impossible to feed filenames with the character colon because
qemu interprets such names as a protocol. For example a filename scsi:0, is
interpreted as a protocol by name "scsi".

This patch allows user to espace colon characters. For example the above
filename can now be expressed either as 'scsi\:0' or as file:scsi:0

anything following the "file:" tag is interpreted verbatim. However if "file:"
tag is omitted then any colon characters in the string must be escaped using
backslash.

Here are couple of examples:

scsi\:0\:abc is a local file scsi:0:abc
http\://myweb is a local file by name http://myweb
file:scsi:0:abc is a local file scsi:0:abc
file:http://myweb is a local file by name http://myweb

Changelog w.r.t to iteration 1:
   1) removes flexibility added to nbd semantics  eg -- nbd:\::9999
   2) introduce the "file:" protocol to indicate local file
 
NOTE: no code changes are needed to handle commas in a filename. As
always a comma has to be escaped by a preceding comma.


Signed-off-by: Ram Pai <address@hidden>
-----------------------------------------------------------------------

 block.c           |   16 ++++++----------
 block/raw-posix.c |   30 +++++++++++++++++++++++-------
 cutils.c          |   26 ++++++++++++++++++++++++++
 qemu-common.h     |    1 +
 4 files changed, 56 insertions(+), 17 deletions(-)

diff --git a/block.c b/block.c
index aca5a6d..0064e22 100644
--- a/block.c
+++ b/block.c
@@ -225,22 +225,18 @@ static BlockDriver *find_protocol(const char *filename)
 {
     BlockDriver *drv1;
     char protocol[128];
-    int len;
-    const char *p;
+    const char *f;
+    int len = strnlen(filename, 128);
 
 #ifdef _WIN32
     if (is_windows_drive(filename) ||
         is_windows_drive_prefix(filename))
         return bdrv_find_format("raw");
 #endif
-    p = strchr(filename, ':');
-    if (!p)
-        return bdrv_find_format("raw");
-    len = p - filename;
-    if (len > sizeof(protocol) - 1)
-        len = sizeof(protocol) - 1;
-    memcpy(protocol, filename, len);
-    protocol[len] = '\0';
+    f = fill_token(protocol, len, filename, ':');
+    if (*f != ':' || !strcmp(protocol, "file"))
+               return bdrv_find_format("raw");
+
     for(drv1 = first_drv; drv1 != NULL; drv1 = drv1->next) {
         if (drv1->protocol_name &&
             !strcmp(drv1->protocol_name, protocol))
diff --git a/block/raw-posix.c b/block/raw-posix.c
index 41bfa37..03d6581 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -124,6 +124,22 @@ static int fd_open(BlockDriverState *bs);
 static int cdrom_reopen(BlockDriverState *bs);
 #endif
 
+static int _open(const char *filename, int flags, ...)
+{
+       char myfile[PATH_MAX];
+       const char *f;
+       va_list ap;
+       va_start(ap, flags);
+
+       if (!strstart(filename, "file:", &f)) {
+               fill_token(myfile, PATH_MAX, filename, '\0');
+               return  open(myfile, flags, ap);
+       } else {
+               return  open(f, flags, ap);
+       }
+}
+
+
 static int raw_open_common(BlockDriverState *bs, const char *filename,
         int flags)
 {
@@ -151,7 +167,7 @@ static int raw_open_common(BlockDriverState *bs, const char 
*filename,
         s->open_flags |= O_DSYNC;
 
     s->fd = -1;
-    fd = open(filename, s->open_flags, 0644);
+    fd = _open(filename, s->open_flags, 0644);
     if (fd < 0) {
         ret = -errno;
         if (ret == -EROFS)
@@ -844,7 +860,7 @@ static int raw_create(const char *filename, 
QEMUOptionParameter *options)
         options++;
     }
 
-    fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
+    fd = _open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
               0644);
     if (fd < 0)
         return -EIO;
@@ -985,7 +1001,7 @@ static int hdev_open(BlockDriverState *bs, const char 
*filename, int flags)
         if ( bsdPath[ 0 ] != '\0' ) {
             strcat(bsdPath,"s0");
             /* some CDs don't have a partition 0 */
-            fd = open(bsdPath, O_RDONLY | O_BINARY | O_LARGEFILE);
+            fd = _open(bsdPath, O_RDONLY | O_BINARY | O_LARGEFILE);
             if (fd < 0) {
                 bsdPath[strlen(bsdPath)-1] = '1';
             } else {
@@ -1037,7 +1053,7 @@ static int fd_open(BlockDriverState *bs)
 #endif
             return -EIO;
         }
-        s->fd = open(bs->filename, s->open_flags & ~O_NONBLOCK);
+        s->fd = _open(bs->filename, s->open_flags & ~O_NONBLOCK);
         if (s->fd < 0) {
             s->fd_error_time = qemu_get_clock(rt_clock);
             s->fd_got_error = 1;
@@ -1133,7 +1149,7 @@ static int hdev_create(const char *filename, 
QEMUOptionParameter *options)
         options++;
     }
 
-    fd = open(filename, O_WRONLY | O_BINARY);
+    fd = _open(filename, O_WRONLY | O_BINARY);
     if (fd < 0)
         return -EIO;
 
@@ -1239,7 +1255,7 @@ static int floppy_eject(BlockDriverState *bs, int 
eject_flag)
         close(s->fd);
         s->fd = -1;
     }
-    fd = open(bs->filename, s->open_flags | O_NONBLOCK);
+    fd = _open(bs->filename, s->open_flags | O_NONBLOCK);
     if (fd >= 0) {
         if (ioctl(fd, FDEJECT, 0) < 0)
             perror("FDEJECT");
@@ -1399,7 +1415,7 @@ static int cdrom_reopen(BlockDriverState *bs)
      */
     if (s->fd >= 0)
         close(s->fd);
-    fd = open(bs->filename, s->open_flags, 0644);
+    fd = _open(bs->filename, s->open_flags, 0644);
     if (fd < 0) {
         s->fd = -1;
         return -EIO;
diff --git a/cutils.c b/cutils.c
index 6ea0c49..f6d5bf5 100644
--- a/cutils.c
+++ b/cutils.c
@@ -24,6 +24,32 @@
 #include "qemu-common.h"
 #include "host-utils.h"
 
+/*
+ * fill buffer 'buff' with the contents of the string 'str' delimited by
+ * the character 'c'. If delimiter not found in 'len' bytes of the string
+ * assume '\0' as the default delimiter.
+ * Return pointer to the delimiting character
+ */
+const char *fill_token(char *buf, int len, const char *str, char c)
+{
+       const char *p=str;
+       char *q=buf;
+
+        while (p < str+len) {
+               if (*p == c) 
+                       break;
+                if (*p == '\\' ) {
+                        p++;
+                       if (*p == '\0')
+                               break;
+               }
+                *q++ = *p++;
+        }
+        *q='\0';
+       return p;
+}
+
+
 void pstrcpy(char *buf, int buf_size, const char *str)
 {
     int c;
diff --git a/qemu-common.h b/qemu-common.h
index 2dcb224..8916502 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -104,6 +104,7 @@ void qemu_get_timedate(struct tm *tm, int offset);
 int qemu_timedate_diff(struct tm *tm);
 
 /* cutils.c */
+const char *fill_token(char *buf, int buf_size, const char *str, char);
 void pstrcpy(char *buf, int buf_size, const char *str);
 char *pstrcat(char *buf, int buf_size, const char *s);
 int strstart(const char *str, const char *val, const char **ptr);