[FFmpeg-devel] lavf/aviobuf: add ff_get_line2() variant

Submitted by Stefano Sabatini on Oct. 20, 2016, 2:05 p.m.

Details

Message ID 20161020140506.GX7148@barisone
State New
Headers show

Commit Message

Stefano Sabatini Oct. 20, 2016, 2:05 p.m.
On date Tuesday 2016-10-18 16:48:02 +0200, Michael Niedermayer encoded:
> On Tue, Oct 18, 2016 at 01:32:12PM +0200, Stefano Sabatini wrote:
[...]
> >  aviobuf.c  |   18 +++++++++++++++---
> >  internal.h |   14 ++++++++++++++
> >  2 files changed, 29 insertions(+), 3 deletions(-)
> > 19b979c45f087997ac69fba2caf5504c933acfc8  0001-lavf-aviobuf-add-ff_get_line2-variant.patch
> > From 58c1cad434447d48246e153e3a1a391d72d23c7b Mon Sep 17 00:00:00 2001
> > From: Stefano Sabatini <stefasab@gmail.com>
> > Date: Thu, 13 Oct 2016 16:36:30 +0200
> > Subject: [PATCH] lavf/aviobuf: add ff_get_line2() variant
> > 
> > This allows to probe if the read line was partially discarded.
> > ---
> >  libavformat/aviobuf.c  | 18 +++++++++++++++---
> >  libavformat/internal.h | 14 ++++++++++++++
> >  2 files changed, 29 insertions(+), 3 deletions(-)
> > 
> > diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
> > index 134d627..29bcf1e 100644
> > --- a/libavformat/aviobuf.c
> > +++ b/libavformat/aviobuf.c
> > @@ -764,18 +764,30 @@ unsigned int avio_rb32(AVIOContext *s)
> >  
> >  int ff_get_line(AVIOContext *s, char *buf, int maxlen)
> >  {
> > -    int i = 0;
> > +    return ff_get_line2(s, buf, maxlen, NULL);
> > +}
> > +
> > +int ff_get_line2(AVIOContext *s, char *buf, int maxlen, int *readlen)
> > +{
> > +    int i = 0, j = 0;
> >      char c;
> >  
> > +    while (1) {
> >          c = avio_r8(s);
> >          if (c && i < maxlen-1)
> >              buf[i++] = c;
> > +        if (c != '\n' && c != '\r' && c) {
> > +            j++;
> > +        } else {
> > +            break;
> > +        }
> > +    }
> 
> a string like "\n"
> would have a strlen of 1
> but readlen of 0
> while a string like "X" would have a strlen and readlen of 1
> 
> is this difference intended ?
> or maybe i misread the code

You're right, I was confused.

Updated patch in attachment, thanks.

Comments

Michael Niedermayer Oct. 20, 2016, 11:18 p.m.
On Thu, Oct 20, 2016 at 04:05:07PM +0200, Stefano Sabatini wrote:
> On date Tuesday 2016-10-18 16:48:02 +0200, Michael Niedermayer encoded:
> > On Tue, Oct 18, 2016 at 01:32:12PM +0200, Stefano Sabatini wrote:
> [...]
> > >  aviobuf.c  |   18 +++++++++++++++---
> > >  internal.h |   14 ++++++++++++++
> > >  2 files changed, 29 insertions(+), 3 deletions(-)
> > > 19b979c45f087997ac69fba2caf5504c933acfc8  0001-lavf-aviobuf-add-ff_get_line2-variant.patch
> > > From 58c1cad434447d48246e153e3a1a391d72d23c7b Mon Sep 17 00:00:00 2001
> > > From: Stefano Sabatini <stefasab@gmail.com>
> > > Date: Thu, 13 Oct 2016 16:36:30 +0200
> > > Subject: [PATCH] lavf/aviobuf: add ff_get_line2() variant
> > > 
> > > This allows to probe if the read line was partially discarded.
> > > ---
> > >  libavformat/aviobuf.c  | 18 +++++++++++++++---
> > >  libavformat/internal.h | 14 ++++++++++++++
> > >  2 files changed, 29 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
> > > index 134d627..29bcf1e 100644
> > > --- a/libavformat/aviobuf.c
> > > +++ b/libavformat/aviobuf.c
> > > @@ -764,18 +764,30 @@ unsigned int avio_rb32(AVIOContext *s)
> > >  
> > >  int ff_get_line(AVIOContext *s, char *buf, int maxlen)
> > >  {
> > > -    int i = 0;
> > > +    return ff_get_line2(s, buf, maxlen, NULL);
> > > +}
> > > +
> > > +int ff_get_line2(AVIOContext *s, char *buf, int maxlen, int *readlen)
> > > +{
> > > +    int i = 0, j = 0;
> > >      char c;
> > >  
> > > +    while (1) {
> > >          c = avio_r8(s);
> > >          if (c && i < maxlen-1)
> > >              buf[i++] = c;
> > > +        if (c != '\n' && c != '\r' && c) {
> > > +            j++;
> > > +        } else {
> > > +            break;
> > > +        }
> > > +    }
> > 
> > a string like "\n"
> > would have a strlen of 1
> > but readlen of 0
> > while a string like "X" would have a strlen and readlen of 1
> > 
> > is this difference intended ?
> > or maybe i misread the code
> 
> You're right, I was confused.
> 
> Updated patch in attachment, thanks.
> -- 
> FFmpeg = Frightening and Fierce Moronic Power Elected Geisha

>  aviobuf.c  |   16 +++++++++++++---
>  internal.h |   14 ++++++++++++++
>  2 files changed, 27 insertions(+), 3 deletions(-)
> ff84236587ab1ebec44e4b835a734757c59fd614  0001-lavf-aviobuf-add-ff_get_line2-variant.patch
> From 54a5d3469d4d9a3f17f45e7577da6c46cb7e969e Mon Sep 17 00:00:00 2001
> From: Stefano Sabatini <stefasab@gmail.com>
> Date: Thu, 13 Oct 2016 16:36:30 +0200
> Subject: [PATCH] lavf/aviobuf: add ff_get_line2() variant
> 
> This allows to probe if the read line was partially discarded.
> ---
>  libavformat/aviobuf.c  | 16 +++++++++++++---
>  libavformat/internal.h | 14 ++++++++++++++
>  2 files changed, 27 insertions(+), 3 deletions(-)

LGTM

thx

[...]

Patch hide | download patch | download mbox

From 54a5d3469d4d9a3f17f45e7577da6c46cb7e969e Mon Sep 17 00:00:00 2001
From: Stefano Sabatini <stefasab@gmail.com>
Date: Thu, 13 Oct 2016 16:36:30 +0200
Subject: [PATCH] lavf/aviobuf: add ff_get_line2() variant

This allows to probe if the read line was partially discarded.
---
 libavformat/aviobuf.c  | 16 +++++++++++++---
 libavformat/internal.h | 14 ++++++++++++++
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
index 134d627..144a617 100644
--- a/libavformat/aviobuf.c
+++ b/libavformat/aviobuf.c
@@ -764,18 +764,28 @@  unsigned int avio_rb32(AVIOContext *s)
 
 int ff_get_line(AVIOContext *s, char *buf, int maxlen)
 {
-    int i = 0;
+    return ff_get_line2(s, buf, maxlen, NULL);
+}
+
+int ff_get_line2(AVIOContext *s, char *buf, int maxlen, int *readlen)
+{
+    int i = 0, j = 0;
     char c;
 
     do {
         c = avio_r8(s);
-        if (c && i < maxlen-1)
-            buf[i++] = c;
+        if (c) {
+            if (i < maxlen-1)
+                buf[i++] = c;
+            j++;
+        }
     } while (c != '\n' && c != '\r' && c);
     if (c == '\r' && avio_r8(s) != '\n' && !avio_feof(s))
         avio_skip(s, -1);
 
     buf[i] = 0;
+    if (readlen)
+        *readlen = j;
     return i;
 }
 
diff --git a/libavformat/internal.h b/libavformat/internal.h
index 49244fa..fc49571 100644
--- a/libavformat/internal.h
+++ b/libavformat/internal.h
@@ -274,6 +274,20 @@  void ff_put_v(AVIOContext *bc, uint64_t val);
  */
 int ff_get_line(AVIOContext *s, char *buf, int maxlen);
 
+/**
+ * Read a whole line of text from AVIOContext. Stop reading after reaching
+ * either a \\n, a \\0 or EOF. The returned string is always \\0-terminated,
+ * and may be truncated if the buffer is too small.
+ *
+ * @param s the read-only AVIOContext
+ * @param buf buffer to store the read line
+ * @param maxlen size of the buffer
+ * @param readlen length of the read line, not including the final \\0
+ * @return the length of the string written in the buffer, not including the
+ *         final \\0
+ */
+int ff_get_line2(AVIOContext *s, char *buf, int maxlen, int *readlen);
+
 #define SPACE_CHARS " \t\r\n"
 
 /**
-- 
1.9.1