From ebecafbd19e2ba55ba90bfc9f7de88f4742479ad Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Sat, 4 May 2019 13:15:29 -0700 Subject: [PATCH] Port new fingerprinting scheme to clang + LTO * lib-src/make-fingerprint.c (main): Don't consider multiple instances of the fingerprint to be an error, as this can happen with clang and -flto. Instead, replace all instances of the fingerprint. There is a tiny chance that this will silently corrupt the Emacs executable. This patch suggests that we should go back to fingerprinting the inputs to the linker instead of its output, as the new fingerprinting scheme is unnecessarily complicated and this complexity reduces reliability. The old scheme (i.e., before commit 2019-05-14T23:31:24Z!eggert@cs.ucla.edu) was simpler and more portable and good enough, and it's looking like it would be less trouble in practice than the new scheme. --- lib-src/make-fingerprint.c | 32 ++++++++++++++------------------ 1 file changed, 14 insertions(+), 18 deletions(-) diff --git a/lib-src/make-fingerprint.c b/lib-src/make-fingerprint.c index 79bd007a5f9..5779e0d2746 100644 --- a/lib-src/make-fingerprint.c +++ b/lib-src/make-fingerprint.c @@ -140,29 +140,25 @@ main (int argc, char **argv) } else { - char *finger = memmem (buf, chunksz, fingerprint, sizeof fingerprint); - if (!finger) - { - fprintf (stderr, "%s: %s: missing fingerprint\n", prog, file); - return EXIT_FAILURE; - } - else if (memmem (finger + 1, buf + chunksz - (finger + 1), - fingerprint, sizeof fingerprint)) - { - fprintf (stderr, "%s: %s: two occurrences of fingerprint\n", - prog, file); - return EXIT_FAILURE; - } + bool fingered = false; - if (fseeko (f, finger - buf, SEEK_SET) != 0) + for (char *finger = buf; + (finger = memmem (finger, buf + chunksz - finger, + fingerprint, sizeof fingerprint)); + finger++) { - perror (file); - return EXIT_FAILURE; + if (! (fseeko (f, finger - buf, SEEK_SET) == 0 + && fwrite (digest, 1, sizeof digest, f) == sizeof digest)) + { + perror (file); + return EXIT_FAILURE; + } + fingered = true; } - if (fwrite (digest, 1, sizeof digest, f) != sizeof digest) + if (!fingered) { - perror (file); + fprintf (stderr, "%s: %s: missing fingerprint\n", prog, file); return EXIT_FAILURE; } } -- 2.39.2