[patch] getline.3: Emphasize that user code should free the allocated buffer even if getline() failed.

[patch] getline.3: Emphasize that user code should free the allocated buffer even if getline() failed.

[Alexey Samsonov]

>From 4a09a0da31e9b98167e974e05f13f57b53dd41c3 Mon Sep 17 00:00:00 2001
From: Alexey Samsonov <samsonov-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Date: Wed, 2 Apr 2014 12:26:44 +0400
Subject: [PATCH] getline.3: Emphasize that user code should free the allocated
 buffer even if getline() failed.

---
 man3/getline.3 | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/man3/getline.3 b/man3/getline.3
index 806e455..9f403a0 100644
--- a/man3/getline.3
+++ b/man3/getline.3
@@ -69,8 +69,11 @@ is set to NULL and
 .I *n
 is set 0 before the call, then
 .BR getline ()
-will allocate a buffer for storing the line,
-which should be freed by the user program.
+will allocate a buffer for storing the line.
+This buffer should be freed by the user program
+even if
+.BR getline ()
+failed.

 Alternatively, before calling
 .BR getline (),
-- 
1.9.1.423.g4596e3a



Relevant discussion in glibc bugzilla:
https://sourceware.org/bugzilla/show_bug.cgi?id=5666
test program:

$ cat tmp/getline/a.cc
#include <stdio.h>
int main() {
  for (int x = 0; x < 2; x++) {
    char *lineptr = 0;
    size_t size = 0;
    int res = getline(&lineptr, &size, stdin);
    printf("%d\n%p\n", res, lineptr);
  }
  return 0;
}
$ gcc tmp/getline/a.cc && echo -n "xxx" > tmp/getline/input && ./a.out
< tmp/getline/input
3
0x11ae010
-1
0x11ae090


-- 
Alexey Samsonov, MSK
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Re: [patch] getline.3: Emphasiqze that user code should free the allocated buffer even if getline() failed.

[Michael Kerrisk (man-pages)]

Hi Alexey,

Good patch, good explanation. Applied. 

Thanks!

Cheers,

Michael



On 04/02/2014 10:30 AM, Alexey Samsonov wrote:
>>From 4a09a0da31e9b98167e974e05f13f57b53dd41c3 Mon Sep 17 00:00:00 2001
> From: Alexey Samsonov <samsonov-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> Date: Wed, 2 Apr 2014 12:26:44 +0400
> Subject: [PATCH] getline.3: Emphasize that user code should free the allocated
>  buffer even if getline() failed.
> 
> ---
>  man3/getline.3 | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/man3/getline.3 b/man3/getline.3
> index 806e455..9f403a0 100644
> --- a/man3/getline.3
> +++ b/man3/getline.3
> @@ -69,8 +69,11 @@ is set to NULL and
>  .I *n
>  is set 0 before the call, then
>  .BR getline ()
> -will allocate a buffer for storing the line,
> -which should be freed by the user program.
> +will allocate a buffer for storing the line.
> +This buffer should be freed by the user program
> +even if
> +.BR getline ()
> +failed.
> 
>  Alternatively, before calling
>  .BR getline (),
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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