diff options
| -rw-r--r-- | doc/fontconfig-user.sgml | 6 | ||||
| -rw-r--r-- | src/fccache.c | 59 |
2 files changed, 58 insertions, 7 deletions
diff --git a/doc/fontconfig-user.sgml b/doc/fontconfig-user.sgml index f4f1c425..89df86ef 100644 --- a/doc/fontconfig-user.sgml +++ b/doc/fontconfig-user.sgml @@ -802,10 +802,14 @@ is used to specify the default language as the weak binding in the query. if thi <emphasis>FONTCONFIG_USE_MMAP</emphasis> is used to control the use of mmap(2) for the cache files if available. this take a boolean value. fontconfig will checks if the cache files are stored on the filesystem that is safe to use mmap(2). explicitly setting this environment variable will causes skipping this check and enforce to use or not use mmap(2) anyway. </para> + <para> +<emphasis>SOURCE_DATE_EPOCH</emphasis> +is used to ensure <literal>fc-cache(1)</literal> generates files in a deterministic manner in order to support reproducible builds. When set to a numeric representation of UNIX timestamp, fontconfig will prefer this value over using the modification timestamps of the input files in order to identify which cache files require regeneration. If <literal>SOURCE_DATE_EPOCH</literal> is not set (or is newer than the mtime of the directory), the existing behaviour is unchanged. + </para> </refsect1> <refsect1><title>See Also</title> <para> -fc-cat(1), fc-cache(1), fc-list(1), fc-match(1), fc-query(1) +fc-cat(1), fc-cache(1), fc-list(1), fc-match(1), fc-query(1), <ulink url="https://reproducible-builds.org/specs/source-date-epoch/">SOURCE_DATE_EPOCH</ulink>. </para> </refsect1> <refsect1><title>Version</title> diff --git a/src/fccache.c b/src/fccache.c index 09e876b0..27b12827 100644 --- a/src/fccache.c +++ b/src/fccache.c @@ -1015,6 +1015,55 @@ FcDirCacheLoadFile (const FcChar8 *cache_file, struct stat *file_stat) return cache; } +static int +FcDirChecksum (struct stat *statb) +{ + int ret = (int) statb->st_mtime; + char *endptr; + char *source_date_epoch; + unsigned long long epoch; + + source_date_epoch = getenv("SOURCE_DATE_EPOCH"); + if (source_date_epoch) + { + epoch = strtoull(source_date_epoch, &endptr, 10); + + if (endptr == source_date_epoch) + fprintf (stderr, + "Fontconfig: SOURCE_DATE_EPOCH invalid\n"); + else if ((errno == ERANGE && (epoch == ULLONG_MAX || epoch == 0)) + || (errno != 0 && epoch == 0)) + fprintf (stderr, + "Fontconfig: SOURCE_DATE_EPOCH: strtoull: %s: %llu\n", + strerror(errno), epoch); + else if (*endptr != '\0') + fprintf (stderr, + "Fontconfig: SOURCE_DATE_EPOCH has trailing garbage\n"); + else if (epoch > ULONG_MAX) + fprintf (stderr, + "Fontconfig: SOURCE_DATE_EPOCH must be <= %lu but saw: %llu\n", + ULONG_MAX, epoch); + else if (epoch < ret) + /* Only override if directory is newer */ + ret = (int) epoch; + } + + return ret; +} + +static int64_t +FcDirChecksumNano (struct stat *statb) +{ +#ifdef HAVE_STRUCT_STAT_ST_MTIM + /* No nanosecond component to parse */ + if (getenv("SOURCE_DATE_EPOCH")) + return 0; + return statb->st_mtim.tv_nsec; +#else + return 0; +#endif +} + /* * Validate a cache file by reading the header and checking * the magic number and the size field @@ -1033,10 +1082,10 @@ FcDirCacheValidateHelper (FcConfig *config, int fd, struct stat *fd_stat, struct ret = FcFalse; else if (fd_stat->st_size != c.size) ret = FcFalse; - else if (c.checksum != (int) dir_stat->st_mtime) + else if (c.checksum != FcDirChecksum (dir_stat)) ret = FcFalse; #ifdef HAVE_STRUCT_STAT_ST_MTIM - else if (c.checksum_nano != dir_stat->st_mtim.tv_nsec) + else if (c.checksum_nano != FcDirChecksumNano (dir_stat)) ret = FcFalse; #endif return ret; @@ -1112,10 +1161,8 @@ FcDirCacheBuild (FcFontSet *set, const FcChar8 *dir, struct stat *dir_stat, FcSt cache->magic = FC_CACHE_MAGIC_ALLOC; cache->version = FC_CACHE_VERSION_NUMBER; cache->size = serialize->size; - cache->checksum = (int) dir_stat->st_mtime; -#ifdef HAVE_STRUCT_STAT_ST_MTIM - cache->checksum_nano = dir_stat->st_mtim.tv_nsec; -#endif + cache->checksum = FcDirChecksum (dir_stat); + cache->checksum_nano = FcDirChecksumNano (dir_stat); /* * Serialize directory name |