On Mon, Aug 26, 2013 at 04:59:01PM -0400, Jeff King wrote:
> Hmm. I wonder if fgetc is a macro in uclibc? Just grepping their
> stdio.h, it looks like that is a possibility.
>
> I think they are probably wrong to do so (but I'd have to check the
> standard). However, the cleaner workaround would probably be to call the
> fgetc struct member something else.
Nope, it's allowed. I think we should do the patch below:
-- >8 --
Subject: config: do not use C function names as struct members
According to C99, section 7.1.4:
Any function declared in a header may be additionally
implemented as a function-like macro defined in the
header.
Therefore calling our struct member function pointer "fgetc"
may run afoul of unwanted macro expansion when we call:
char c = cf->fgetc(cf);
This turned out to be a problem on uclibc, which defines
fgetc as a macro and causes compilation failure.
The standard suggests fixing this in a few ways:
1. Using extra parentheses to inhibit the function-like
macro expansion. E.g., "(cf->fgetc)(cf)". This is
undesirable as it's ugly, and each call site needs to
remember to use it (and on systems without the macro,
forgetting will compile just fine).
2. Using #undef (because a conforming implementation must
also be providing fgetc as a function). This is
undesirable because presumably the implementation was
using the macro for a performance benefit, and we are
dropping that optimization.
Instead, we can simply use non-colliding names.
Signed-off-by: Jeff King <peff@xxxxxxxx>
---
config.c | 32 ++++++++++++++++----------------
1 file changed, 16 insertions(+), 16 deletions(-)
diff --git a/config.c b/config.c
index e13a7b6..9f9bf0c 100644
--- a/config.c
+++ b/config.c
@@ -27,9 +27,9 @@ struct config_source {
struct strbuf value;
struct strbuf var;
- int (*fgetc)(struct config_source *c);
- int (*ungetc)(int c, struct config_source *conf);
- long (*ftell)(struct config_source *c);
+ int (*do_fgetc)(struct config_source *c);
+ int (*do_ungetc)(int c, struct config_source *conf);
+ long (*do_ftell)(struct config_source *c);
};
static struct config_source *cf;
@@ -217,13 +217,13 @@ static int get_next_char(void)
static int get_next_char(void)
{
- int c = cf->fgetc(cf);
+ int c = cf->do_fgetc(cf);
if (c == '\r') {
/* DOS like systems */
- c = cf->fgetc(cf);
+ c = cf->do_fgetc(cf);
if (c != '\n') {
- cf->ungetc(c, cf);
+ cf->do_ungetc(c, cf);
c = '\r';
}
}
@@ -992,9 +992,9 @@ int git_config_from_file(config_fn_t fn, const char *filename, void *data)
top.u.file = f;
top.name = filename;
top.die_on_error = 1;
- top.fgetc = config_file_fgetc;
- top.ungetc = config_file_ungetc;
- top.ftell = config_file_ftell;
+ top.do_fgetc = config_file_fgetc;
+ top.do_ungetc = config_file_ungetc;
+ top.do_ftell = config_file_ftell;
ret = do_config_from(&top, fn, data);
@@ -1013,9 +1013,9 @@ int git_config_from_buf(config_fn_t fn, const char *name, const char *buf,
top.u.buf.pos = 0;
top.name = name;
top.die_on_error = 0;
- top.fgetc = config_buf_fgetc;
- top.ungetc = config_buf_ungetc;
- top.ftell = config_buf_ftell;
+ top.do_fgetc = config_buf_fgetc;
+ top.do_ungetc = config_buf_ungetc;
+ top.do_ftell = config_buf_ftell;
return do_config_from(&top, fn, data);
}
@@ -1196,7 +1196,7 @@ static int store_aux(const char *key, const char *value, void *cb)
return 1;
}
- store.offset[store.seen] = cf->ftell(cf);
+ store.offset[store.seen] = cf->do_ftell(cf);
store.seen++;
}
break;
@@ -1223,19 +1223,19 @@ static int store_aux(const char *key, const char *value, void *cb)
* Do not increment matches: this is no match, but we
* just made sure we are in the desired section.
*/
- store.offset[store.seen] = cf->ftell(cf);
+ store.offset[store.seen] = cf->do_ftell(cf);
/* fallthru */
case SECTION_END_SEEN:
case START:
if (matches(key, value)) {
- store.offset[store.seen] = cf->ftell(cf);
+ store.offset[store.seen] = cf->do_ftell(cf);
store.state = KEY_SEEN;
store.seen++;
} else {
if (strrchr(key, '.') - key == store.baselen &&
!strncmp(key, store.key, store.baselen)) {
store.state = SECTION_SEEN;
- store.offset[store.seen] = cf->ftell(cf);
+ store.offset[store.seen] = cf->do_ftell(cf);
}
}
}
--
1.8.4.2.g87d4a77
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