Don't expose 'detach_buffer()' to membuffer users

The native buffer of a membuffer is not NUL-terminated, so when you want
to detach it and use it as a C string, you had to first do
'mb_cstring()' that adds the proper termination/

This was all documented in the header files, and all but two users did
it correctly.

But there were those two users, and the exported interface was
unnecessarily hard to use.  We do want the "just detach the raw buffer"
internally in the membuffer code, but let's not make the exported
interface be that hard to use.

So this switches the exported interface to be 'detach_cstring()', which
does that 'mb_cstring()' for you, and avoids the possibility that you'd
use a non-terminated memory buffer as a C string.

The old 'detach_buffer()' is now purely the internal membuffer
implementation, and not used by others.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2019-10-27 14:24:10 -04:00 committed by Dirk Hohndel
parent d401271dab
commit a9b1fbdcc5
7 changed files with 20 additions and 22 deletions

View file

@ -22,8 +22,7 @@ int report_error(const char *fmt, ...)
return -1;
VA_BUF(&buf, fmt);
mb_cstring(&buf);
error_cb(detach_buffer(&buf));
error_cb(detach_cstring(&buf));
return -1;
}

View file

@ -12,7 +12,8 @@
#include "dive.h"
#include "membuffer.h"
char *detach_buffer(struct membuffer *b)
/* Only for internal use */
static char *detach_buffer(struct membuffer *b)
{
char *result = b->buffer;
b->buffer = NULL;
@ -21,6 +22,12 @@ char *detach_buffer(struct membuffer *b)
return result;
}
char *detach_cstring(struct membuffer *b)
{
mb_cstring(b);
return detach_buffer(b);
}
void free_buffer(struct membuffer *b)
{
free(detach_buffer(b));
@ -117,8 +124,7 @@ char *vformat_string(const char *fmt, va_list args)
{
struct membuffer mb = { 0 };
put_vformat(&mb, fmt, args);
mb_cstring(&mb);
return detach_buffer(&mb);
return detach_cstring(&mb);
}
char *format_string(const char *fmt, ...)

View file

@ -23,17 +23,13 @@
*
* "something, something else"
*
* Unless ownership to the buffer is given away say to a caller
* Unless ownership to the buffer is given away by using "detach_cstring()":
*
* mb_cstring(&mb);
* return detach_buffer(&mb);
* ptr = detach_cstring();
*
* or via a callback
* where the caller now has a C string and is supposed to free it.
*
* mb_cstring(&mb);
* cb(detach_buffer(&mb));
*
* otherwise allocated memory should be freed
* Otherwise allocated memory should be freed
*
* free_buffer(&mb);
*/
@ -60,7 +56,7 @@ struct membuffer {
#define __printf(x, y)
#endif
extern char *detach_buffer(struct membuffer *b);
extern char *detach_cstring(struct membuffer *b);
extern void free_buffer(struct membuffer *);
extern void make_room(struct membuffer *b, unsigned int size);
extern void flush_buffer(struct membuffer *, FILE *);

View file

@ -89,7 +89,7 @@ char *get_planner_disclaimer_formatted()
const char *deco = decoMode() == VPMB ? translate("gettextFromC", "VPM-B")
: translate("gettextFromC", "BUHLMANN");
put_format(&buf, get_planner_disclaimer(), deco);
return detach_buffer(&buf);
return detach_cstring(&buf);
}
void add_plan_to_notes(struct diveplan *diveplan, struct dive *dive, bool show_disclaimer, int error)
@ -618,9 +618,8 @@ void add_plan_to_notes(struct diveplan *diveplan, struct dive *dive, bool show_d
if (o2warning_exist)
put_string(&buf, "</div>\n");
finished:
mb_cstring(&buf);
free(dive->notes);
dive->notes = detach_buffer(&buf);
dive->notes = detach_cstring(&buf);
#ifdef DEBUG_PLANNER_NOTES
printf("<!DOCTYPE html>\n<html>\n\t<head><title>plannernotes</title><meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\"/></head>\n\t<body>\n%s\t</body>\n</html>\n", dive->notes);
#endif

View file

@ -72,8 +72,7 @@ char *taglist_get_tagstring(struct tag_entry *tag_list)
* - empty tag list
* - tag list with empty tag only
*/
mb_cstring(&b);
return detach_buffer(&b);
return detach_cstring(&b);
}
static inline void taglist_free_divetag(struct divetag *tag)

View file

@ -60,8 +60,7 @@ void subsurface_user_info(struct user_info *user)
struct membuffer mb = {};
gethostname(hostname, sizeof(hostname));
put_format(&mb, "%s@%s", username, hostname);
mb_cstring(&mb);
user->email = detach_buffer(&mb);
user->email = detach_cstring(&mb);
}
}

View file

@ -132,7 +132,7 @@ void TabDivePhotos::saveSubtitles()
continue;
struct membuffer b = { 0 };
save_subtitles_buffer(&b, &displayed_dive, offset, duration);
char *data = detach_buffer(&b);
char *data = detach_cstring(&b);
subtitlefile.open(QIODevice::WriteOnly);
subtitlefile.write(data, strlen(data));
subtitlefile.close();