From 73be01623bc2b1cb1618d283fff07fe96cd87499 Mon Sep 17 00:00:00 2001 From: Tristan Riehs Date: Thu, 25 Dec 2025 12:57:27 +0100 Subject: Add routine for computing file sum --- src/main.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) (limited to 'src') diff --git a/src/main.c b/src/main.c index 7bae17c..0dd5633 100644 --- a/src/main.c +++ b/src/main.c @@ -95,6 +95,36 @@ static void sanitize_sql_str(char **str) *str = new_str; } +/* Compute something that identifies the content of FILE and write it to + OUT. Algorithm from http://www.cse.yorku.ca/~oz/hash.html via + https://stackoverflow.com/a/7666577/20138083. Return 0 on success, -1 on + error. */ +static int sum(uint64_t *out, const char *file) +{ + FILE *stream = fopen(file, "r"); + uint8_t buf[4096]; + size_t buf_len; + uint64_t sum = 5381; + if (!file) { + perror("fopen"); + return -1; + } + while ((buf_len = fread(&buf, 1, sizeof(buf), stream)) != 0) { + for (int i = 0; i < buf_len; i++) { + uint8_t next = buf[i]; + sum = sum*33 + next; + } + } + if (ferror(stream)) { + perror("fread"); + fclose(stream); + return -1; + } + fclose(stream); + *out = sum; + return 0; +} + static time_t time_from_str(const char *str) { int rc; -- cgit v1.2.3