From ed0296b9055713df0d910e4e7528ffe6fc539514 Mon Sep 17 00:00:00 2001 From: Mattias Andrée Date: Sun, 10 Feb 2019 20:21:19 +0100 Subject: First commit MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Mattias Andrée --- sum_fd.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 sum_fd.c (limited to 'sum_fd.c') diff --git a/sum_fd.c b/sum_fd.c new file mode 100644 index 0000000..bc2761d --- /dev/null +++ b/sum_fd.c @@ -0,0 +1,45 @@ +/* See LICENSE file for copyright and license details. */ +#include "common.h" + + +/** + * Calculate the checksum for a file, + * the content of the file is assumed non-sensitive + * + * @param fd The file descriptor of the file + * @param algorithm The hashing algorithm + * @param hashsum Output buffer for the hash + * @return Zero on success, -1 on error + */ +int +libsha1_sum_fd(int fd, enum libsha1_algorithm algorithm, void *restrict hashsum) +{ + struct libsha1_state state; + ssize_t r; + struct stat attr; + size_t blksize = 4096; + char *restrict chunk; + + if (libsha1_init(&state, algorithm) < 0) + return -1; + + if (fstat(fd, &attr) == 0 && attr.st_blksize > 0) + blksize = (size_t)(attr.st_blksize); + + chunk = alloca(blksize); + + for (;;) { + r = read(fd, chunk, blksize); + if (r <= 0) { + if (!r) + break; + if (errno == EINTR) + continue; + return -1; + } + libsha1_update(&state, chunk, (size_t)r * 8); + } + + libsha1_digest(&state, NULL, 0, hashsum); + return 0; +} -- cgit v1.2.3-70-g09d2