diff options
| author | David Herrmann <dh.herrmann@gmail.com> | 2014-12-12 09:43:54 +0100 |
|---|---|---|
| committer | David Herrmann <dh.herrmann@gmail.com> | 2014-12-12 09:43:54 +0100 |
| commit | bff686e2a981ccd0888cdf1981977d24320f1770 (patch) | |
| tree | 985439518c0dd5c3b3b7f9361d604e743c1d41ec /src | |
| parent | 0b9315719154fa7ea1a075e1b3785713f5acc3a1 (diff) | |
hwdb: fix dangling 'else' ambuguity
Imagine the following use of hwdb:
if (condition_A)
SD_HWDB_FOREACH_PROPERTY(hwdb, modalias, key, value)
operation_A(key, value);
else
log_error("...");
This should work just fine, but but definitely does not what you would
expect. Due to how SD_HWDB_FOREACH_PROPERTY is defined, the dangling
'else' is linked to the hidden 'if' statement in the macro instead of the
outer 'if (condition_A)'. This is unexpected and really annoying to debug.
Fix this by never leaving un-finished if-statements in
SD_HWDB_FOREACH_PROPERTY(). We simply inverse the if() statement and
explicitly add an 'else'-branch. This way, the statement is closed and all
ambuguities are resolved.
Diffstat (limited to 'src')
| -rw-r--r-- | src/systemd/sd-hwdb.h | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/src/systemd/sd-hwdb.h b/src/systemd/sd-hwdb.h index f41555df7e..3c44b981d6 100644 --- a/src/systemd/sd-hwdb.h +++ b/src/systemd/sd-hwdb.h @@ -39,8 +39,9 @@ int sd_hwdb_get(sd_hwdb *hwdb, const char *modalias, const char *key, const char int sd_hwdb_seek(sd_hwdb *hwdb, const char *modalias); int sd_hwdb_enumerate(sd_hwdb *hwdb, const char **key, const char **value); +/* the inverse condition avoids ambiguity of danling 'else' after the macro */ #define SD_HWDB_FOREACH_PROPERTY(hwdb, modalias, key, value) \ - if (sd_hwdb_seek(hwdb, modalias) >= 0) \ - while (sd_hwdb_enumerate(hwdb, &(key), &(value)) > 0) + if (sd_hwdb_seek(hwdb, modalias) < 0) { } \ + else while (sd_hwdb_enumerate(hwdb, &(key), &(value)) > 0) #endif |