lavu: add escape API

The escape API will be useful to perform escaping programmatically, which
is required when crafting argument strings, and will be used for context
printing as well.

This is based on the ffescape tool code, with a few extensions and fixes.

1 files changed, 45 insertions, 0 deletions

diff --git a/libavutil/bprint.c b/libavutil/bprint.c
index 4684ab4979..fd7611aaed 100644
--- a/libavutil/bprint.c
+++ b/libavutil/bprint.c
@@ -23,6 +23,7 @@
 #include <string.h>
 #include <time.h>
 #include "avassert.h"
+#include "avstring.h"
 #include "bprint.h"
 #include "common.h"
 #include "error.h"
@@ -217,6 +218,50 @@ int av_bprint_finalize(AVBPrint *buf, char **ret_str)
     return ret;
 }
 
+#define WHITESPACES " \n\t"
+
+void av_bprint_escape(AVBPrint *dstbuf, const char *src, const char *special_chars,
+                      enum AVEscapeMode mode, int flags)
+{
+    const char *src0 = src;
+
+    if (mode == AV_ESCAPE_MODE_AUTO)
+        mode = AV_ESCAPE_MODE_BACKSLASH; /* TODO: implement a heuristic */
+
+    switch (mode) {
+    case AV_ESCAPE_MODE_QUOTE:
+        /* enclose the string between '' */
+        av_bprint_chars(dstbuf, '\'', 1);
+        for (; *src; src++) {
+            if (*src == '\'')
+                av_bprintf(dstbuf, "'\\''");
+            else
+                av_bprint_chars(dstbuf, *src, 1);
+        }
+        av_bprint_chars(dstbuf, '\'', 1);
+        break;
+
+    /* case AV_ESCAPE_MODE_BACKSLASH or unknown mode */
+    default:
+        /* \-escape characters */
+        for (; *src; src++) {
+            int is_first_last       = src == src0 || !*(src+1);
+            int is_ws               = !!strchr(WHITESPACES, *src);
+            int is_strictly_special = special_chars && strchr(special_chars, *src);
+            int is_special          =
+                is_strictly_special || strchr("'\\", *src) ||
+                (is_ws && (flags & AV_ESCAPE_FLAG_WHITESPACE));
+
+            if (is_strictly_special ||
+                (!(flags & AV_ESCAPE_FLAG_STRICT) &&
+                 (is_special || (is_ws && is_first_last))))
+                av_bprint_chars(dstbuf, '\\', 1);
+            av_bprint_chars(dstbuf, *src, 1);
+        }
+        break;
+    }
+}
+
 #ifdef TEST
 
 #undef printf