[gimp] app: improve file magic matching
- From: Michael Natterer <mitch src gnome org>
- To: commits-list gnome org
- Cc:
- Subject: [gimp] app: improve file magic matching
- Date: Sun, 24 Apr 2016 22:06:48 +0000 (UTC)
commit 6af83a5a08435db238c87d7046a254bacfbb6879
Author: Michael Natterer <mitch gimp org>
Date: Sun Apr 24 23:56:57 2016 +0200
app: improve file magic matching
Change file magic matching from using a simple boolean "magic matches"
logic to using a matching quality. The quality is measured by the
number of bytes that matched.
Matching a single file procedure's magics now tries all magics and
returns the best match quality.
Searching a file procedure for a given file now tries all file
procedures and returns the one with the best match quality.
This fixes raw camera files being opened as TIFF, given a better magic
than just the generic TIFF magic is provided.
app/plug-in/gimppluginmanager-file-procedure.c | 205 +++++++++++++++++-------
1 files changed, 145 insertions(+), 60 deletions(-)
---
diff --git a/app/plug-in/gimppluginmanager-file-procedure.c b/app/plug-in/gimppluginmanager-file-procedure.c
index 24e9956..27a0eb9 100644
--- a/app/plug-in/gimppluginmanager-file-procedure.c
+++ b/app/plug-in/gimppluginmanager-file-procedure.c
@@ -40,9 +40,10 @@
typedef enum
{
- FILE_MATCH_NONE,
- FILE_MATCH_MAGIC,
- FILE_MATCH_SIZE
+ /* positive values indicate the lenght of a matching magic */
+
+ FILE_MATCH_NONE = 0,
+ FILE_MATCH_SIZE = -1
} FileMatchType;
@@ -116,11 +117,13 @@ file_procedure_find (GSList *procs,
/* Then look for magics, but not on remote files */
if (g_file_is_native (file))
{
- GSList *list;
- GInputStream *input = NULL;
- gboolean opened = FALSE;
- gsize head_size = 0;
- guchar head[256];
+ GSList *list;
+ GInputStream *input = NULL;
+ gboolean opened = FALSE;
+ gsize head_size = 0;
+ guchar head[256];
+ FileMatchType best_match_val = FILE_MATCH_NONE;
+ GimpPlugInProcedure *best_file_proc = NULL;
for (list = procs; list; list = g_slist_next (list))
{
@@ -172,24 +175,28 @@ file_procedure_find (GSList *procs,
}
else if (match_val != FILE_MATCH_NONE)
{
- g_object_unref (input);
+ g_printerr ("magic match %d on %s\n",
+ match_val,
+ gimp_object_get_name (file_proc));
- return file_proc;
+ if (match_val > best_match_val)
+ {
+ best_match_val = match_val;
+ best_file_proc = file_proc;
+ }
}
}
}
}
if (input)
+ g_object_unref (input);
+
+ if (best_file_proc)
{
-#if 0
- if (ferror (ifp))
- g_set_error_literal (error, G_FILE_ERROR,
- g_file_error_from_errno (errno),
- g_strerror (errno));
-#endif
-
- g_object_unref (input);
+ g_printerr ("best magic match on %s\n",
+ gimp_object_get_name (best_file_proc));
+ return best_file_proc;
}
}
@@ -414,7 +421,7 @@ file_check_single_magic (const gchar *offset,
FileMatchType found = FILE_MATCH_NONE;
glong offs;
gulong num_testval;
- gulong num_operatorval;
+ gulong num_operator_val;
gint numbytes, k;
const gchar *num_operator_ptr;
gchar num_operator;
@@ -461,18 +468,20 @@ file_check_single_magic (const gchar *offset,
if (g_ascii_isdigit (num_operator_ptr[1]))
{
if (num_operator_ptr[1] != '0') /* decimal */
- sscanf (num_operator_ptr+1, "%lu", &num_operatorval);
+ sscanf (num_operator_ptr+1, "%lu", &num_operator_val);
else if (num_operator_ptr[2] == 'x') /* hexadecimal */
- sscanf (num_operator_ptr+3, "%lx", &num_operatorval);
+ sscanf (num_operator_ptr+3, "%lx", &num_operator_val);
else /* octal */
- sscanf (num_operator_ptr+2, "%lo", &num_operatorval);
+ sscanf (num_operator_ptr+2, "%lo", &num_operator_val);
num_operator = *num_operator_ptr;
}
}
- if (numbytes > 0) /* Numerical test ? */
+ if (numbytes > 0)
{
+ /* Numerical test */
+
gchar num_test = '=';
gulong fileval = 0;
@@ -489,8 +498,10 @@ file_check_single_magic (const gchar *offset,
if (errno != 0)
return FILE_MATCH_NONE;
- if (numbytes == 5) /* Check for file size ? */
+ if (numbytes == 5)
{
+ /* Check for file size */
+
GFileInfo *info = g_file_query_info (file,
G_FILE_ATTRIBUTE_STANDARD_SIZE,
G_FILE_QUERY_INFO_NONE,
@@ -502,13 +513,17 @@ file_check_single_magic (const gchar *offset,
g_object_unref (info);
}
else if (offs >= 0 &&
- (offs + numbytes <= headsize)) /* We have it in memory ? */
+ (offs + numbytes <= headsize))
{
+ /* We have it in memory */
+
for (k = 0; k < numbytes; k++)
fileval = (fileval << 8) | (glong) file_head[offs + k];
}
- else /* Read it from file */
+ else
{
+ /* Read it from file */
+
if (! g_seekable_seek (G_SEEKABLE (input), offs,
(offs >= 0) ? G_SEEK_SET : G_SEEK_END,
NULL, NULL))
@@ -532,20 +547,31 @@ file_check_single_magic (const gchar *offset,
}
if (num_operator == '&')
- fileval &= num_operatorval;
+ fileval &= num_operator_val;
if (num_test == '<')
- found = (fileval < num_testval);
+ {
+ if (fileval < num_testval)
+ found = numbytes;
+ }
else if (num_test == '>')
- found = (fileval > num_testval);
+ {
+ if (fileval > num_testval)
+ found = numbytes;
+ }
else
- found = (fileval == num_testval);
+ {
+ if (fileval == num_testval)
+ found = numbytes;
+ }
if (found && (numbytes == 5))
found = FILE_MATCH_SIZE;
}
- else if (numbytes == 0) /* String test */
+ else if (numbytes == 0)
{
+ /* String test */
+
gchar mem_testval[256];
file_convert_string (value,
@@ -556,20 +582,23 @@ file_check_single_magic (const gchar *offset,
return FILE_MATCH_NONE;
if (offs >= 0 &&
- (offs + numbytes <= headsize)) /* We have it in memory ? */
+ (offs + numbytes <= headsize))
{
- found = (memcmp (mem_testval, file_head + offs, numbytes) == 0);
+ /* We have it in memory */
+
+ if (memcmp (mem_testval, file_head + offs, numbytes) == 0)
+ found = numbytes;
}
- else /* Read it from file */
+ else
{
+ /* Read it from file */
+
if (! g_seekable_seek (G_SEEKABLE (input), offs,
(offs >= 0) ? G_SEEK_SET : G_SEEK_END,
NULL, NULL))
return FILE_MATCH_NONE;
- found = FILE_MATCH_MAGIC;
-
- for (k = 0; found && (k < numbytes); k++)
+ for (k = 0; k < numbytes; k++)
{
guchar byte;
GError *error = NULL;
@@ -579,12 +608,15 @@ file_check_single_magic (const gchar *offset,
if (error)
{
g_clear_error (&error);
+
return FILE_MATCH_NONE;
}
if (byte != mem_testval[k])
- found = FILE_MATCH_NONE;
+ return FILE_MATCH_NONE;
}
+
+ found = numbytes;
}
}
@@ -599,36 +631,89 @@ file_check_magic_list (GSList *magics_list,
GInputStream *input)
{
- const gchar *offset;
- const gchar *type;
- const gchar *value;
- gboolean and = FALSE;
- gboolean found = FALSE;
- FileMatchType match_val;
-
- while (magics_list)
+ gboolean and = FALSE;
+ gboolean found = FALSE;
+ FileMatchType best_match_val = FILE_MATCH_NONE;
+ FileMatchType match_val = FILE_MATCH_NONE;
+
+ for (; magics_list; magics_list = magics_list->next)
{
- if ((offset = magics_list->data) == NULL) break;
- if ((magics_list = magics_list->next) == NULL) break;
- if ((type = magics_list->data) == NULL) break;
- if ((magics_list = magics_list->next) == NULL) break;
- if ((value = magics_list->data) == NULL) break;
+ const gchar *offset;
+ const gchar *type;
+ const gchar *value;
+ FileMatchType single_match_val = FILE_MATCH_NONE;
- magics_list = magics_list->next;
+ if ((offset = magics_list->data) == NULL) return FILE_MATCH_NONE;
+ if ((magics_list = magics_list->next) == NULL) return FILE_MATCH_NONE;
+ if ((type = magics_list->data) == NULL) return FILE_MATCH_NONE;
+ if ((magics_list = magics_list->next) == NULL) return FILE_MATCH_NONE;
+ if ((value = magics_list->data) == NULL) return FILE_MATCH_NONE;
+
+ single_match_val = file_check_single_magic (offset, type, value,
+ head, headsize,
+ file, input);
- match_val = file_check_single_magic (offset, type, value,
- head, headsize,
- file, input);
if (and)
- found = found && (match_val != FILE_MATCH_NONE);
+ found = found && (single_match_val != FILE_MATCH_NONE);
else
- found = (match_val != FILE_MATCH_NONE);
+ found = (single_match_val != FILE_MATCH_NONE);
+
+ if (match_val == FILE_MATCH_NONE)
+ {
+ /* if we have no match yet, this is it in any case */
+
+ match_val = single_match_val;
+ }
+ else if (single_match_val != FILE_MATCH_NONE)
+ {
+ /* else if we have a match on this one, combine it with the
+ * existing return value
+ */
+
+ if (single_match_val == FILE_MATCH_SIZE)
+ {
+ /* if we already have a magic match, simply increase
+ * that by one to indicate "better match", not perfect
+ * but better than losing the additional size match
+ * entirely
+ */
+ if (match_val != FILE_MATCH_SIZE)
+ match_val += 1;
+ }
+ else
+ {
+ /* if we already have a magic match, simply add to its
+ * length; otherwise if we already have a size match,
+ * combine it with this match, see comment above
+ */
+ if (match_val != FILE_MATCH_SIZE)
+ match_val += single_match_val;
+ else
+ match_val = single_match_val + 1;
+ }
+ }
+
+ if (best_match_val == FILE_MATCH_NONE)
+ {
+ /* if we have no best match yet, this is it */
+
+ best_match_val = match_val;
+ }
+ else if (match_val != FILE_MATCH_NONE)
+ {
+ /* otherwise if this was a match, update the best match, note
+ * that by using MAX we will not overwrite a magic match
+ * with a size match
+ */
+
+ best_match_val = MAX (best_match_val, match_val);
+ }
and = (strchr (offset, '&') != NULL);
- if (! and && found)
- return match_val;
+ if (! and)
+ match_val = FILE_MATCH_NONE;
}
- return FILE_MATCH_NONE;
+ return best_match_val;
}
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