Most parser functions take a **endp argument to indicate the caller
where parsing has stopped. This is currently only used after parsing
something successfully. This patch sets **endp to the erroneous
position in the error case and prints its position after an error
has occured.

Signed-off-by: Sascha Hauer <s.ha...@pengutronix.de>
---
 src/mediactl.c | 48 +++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 45 insertions(+), 3 deletions(-)

diff --git a/src/mediactl.c b/src/mediactl.c
index c65de50..04ade15 100644
--- a/src/mediactl.c
+++ b/src/mediactl.c
@@ -40,6 +40,22 @@
 #include "mediactl.h"
 #include "tools.h"
 
+void media_print_streampos(struct media_device *media, const char *p, const 
char *end)
+{
+       int pos;
+
+       pos = end - p + 1;
+
+       if (pos < 0)
+               pos = 0;
+       if (pos > strlen(p))
+               pos = strlen(p);
+
+       media_dbg(media, "\n");
+       media_dbg(media, " %s\n", p);
+       media_dbg(media, " %*s\n", pos, "^");
+}
+
 struct media_pad *media_entity_remote_source(struct media_pad *pad)
 {
        unsigned int i;
@@ -538,12 +554,16 @@ struct media_pad *media_parse_pad(struct media_device 
*media,
        if (*p == '"') {
                for (end = (char *)p + 1; *end && *end != '"'; ++end);
                if (*end != '"') {
+                       if (endp)
+                               *endp = (char *)end;
                        media_dbg(media, "missing matching '\"'\n");
                        return NULL;
                }
 
                entity = media_get_entity_by_name(media, p + 1, end - p - 1);
                if (entity == NULL) {
+                       if (endp)
+                               *endp = (char *)p + 1;
                        media_dbg(media, "no such entity \"%.*s\"\n", end - p - 
1, p + 1);
                        return NULL;
                }
@@ -553,6 +573,8 @@ struct media_pad *media_parse_pad(struct media_device 
*media,
                entity_id = strtoul(p, &end, 10);
                entity = media_get_entity_by_id(media, entity_id);
                if (entity == NULL) {
+                       if (endp)
+                               *endp = (char *)p;
                        media_dbg(media, "no such entity %d\n", entity_id);
                        return NULL;
                }
@@ -560,6 +582,8 @@ struct media_pad *media_parse_pad(struct media_device 
*media,
        for (; isspace(*end); ++end);
 
        if (*end != ':') {
+               if (endp)
+                       *endp = end;
                media_dbg(media, "Expected ':'\n", *end);
                return NULL;
        }
@@ -569,6 +593,8 @@ struct media_pad *media_parse_pad(struct media_device 
*media,
        pad = strtoul(p, &end, 10);
 
        if (pad >= entity->info.pads) {
+               if (endp)
+                       *endp = (char *)p;
                media_dbg(media, "No pad '%d' on entity \"%s\". Maximum pad 
number is %d\n",
                                pad, entity->info.name, entity->info.pads - 1);
                return NULL;
@@ -591,10 +617,15 @@ struct media_link *media_parse_link(struct media_device 
*media,
        char *end;
 
        source = media_parse_pad(media, p, &end);
-       if (source == NULL)
+       if (source == NULL) {
+               if (endp)
+                       *endp = end;
                return NULL;
+       }
 
        if (end[0] != '-' || end[1] != '>') {
+               if (endp)
+                       *endp = end;
                media_dbg(media, "Expected '->'\n");
                return NULL;
        }
@@ -602,8 +633,11 @@ struct media_link *media_parse_link(struct media_device 
*media,
        p = end + 2;
 
        sink = media_parse_pad(media, p, &end);
-       if (sink == NULL)
+       if (sink == NULL) {
+               if (endp)
+                       *endp = end;
                return NULL;
+       }
 
        *endp = end;
 
@@ -629,6 +663,8 @@ int media_parse_setup_link(struct media_device *media,
 
        link = media_parse_link(media, p, &end);
        if (link == NULL) {
+               if (endp)
+                       *endp = end;
                media_dbg(media,
                          "%s: Unable to parse link\n", __func__);
                return -EINVAL;
@@ -636,6 +672,8 @@ int media_parse_setup_link(struct media_device *media,
 
        p = end;
        if (*p++ != '[') {
+               if (endp)
+                       *endp = (char *)p - 1;
                media_dbg(media, "Unable to parse link flags: expected '['.\n");
                return -EINVAL;
        }
@@ -643,6 +681,8 @@ int media_parse_setup_link(struct media_device *media,
        flags = strtoul(p, &end, 10);
        for (p = end; isspace(*p); p++);
        if (*p++ != ']') {
+               if (endp)
+                       *endp = (char *)p - 1;
                media_dbg(media, "Unable to parse link flags: expected ']'.\n");
                return -EINVAL;
        }
@@ -666,8 +706,10 @@ int media_parse_setup_links(struct media_device *media, 
const char *p)
 
        do {
                ret = media_parse_setup_link(media, p, &end);
-               if (ret < 0)
+               if (ret < 0) {
+                       media_print_streampos(media, p, end);
                        return ret;
+               }
 
                p = end + 1;
        } while (*end == ',');
-- 
1.8.2.rc2

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