From: Emil Velikov Date: Mon, 12 Feb 2024 17:23:10 +0000 (+0000) Subject: libkmod: swap alloca usage for a few assert_cc X-Git-Tag: v33~58 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=737744301a992ed55801acb725995746bdad62a1;p=thirdparty%2Fkmod.git libkmod: swap alloca usage for a few assert_cc Since all the compression magic is always available now, we don't need to loop at runtime nor use alloca - latter of which comes with a handful of caveats. Simply throw in a few assert_cc(), which will trigger at build-time. Signed-off-by: Emil Velikov Reviewed-by: Lucas De Marchi Signed-off-by: Lucas De Marchi --- diff --git a/libkmod/libkmod-file.c b/libkmod/libkmod-file.c index b69f1ef6..5b88d6c9 100644 --- a/libkmod/libkmod-file.c +++ b/libkmod/libkmod-file.c @@ -410,7 +410,6 @@ struct kmod_file *kmod_file_open(const struct kmod_ctx *ctx, { struct kmod_file *file = calloc(1, sizeof(struct kmod_file)); const struct comp_type *itr; - size_t magic_size_max = 0; int err = 0; if (file == NULL) @@ -422,22 +421,17 @@ struct kmod_file *kmod_file_open(const struct kmod_ctx *ctx, goto error; } - for (itr = comp_types; itr->load != NULL; itr++) { - if (magic_size_max < itr->magic_size) - magic_size_max = itr->magic_size; - } - - if (magic_size_max > 0) { - char *buf = alloca(magic_size_max + 1); + { + char buf[7]; ssize_t sz; - if (buf == NULL) { - err = -errno; - goto error; - } - sz = read_str_safe(file->fd, buf, magic_size_max + 1); + assert_cc(sizeof(magic_zstd) < sizeof(buf)); + assert_cc(sizeof(magic_xz) < sizeof(buf)); + assert_cc(sizeof(magic_zlib) < sizeof(buf)); + + sz = read_str_safe(file->fd, buf, sizeof(buf)); lseek(file->fd, 0, SEEK_SET); - if (sz != (ssize_t)magic_size_max) { + if (sz != (sizeof(buf) - 1)) { if (sz < 0) err = sz; else