diff options
| -rw-r--r-- | include/util.h | 6 | ||||
| -rw-r--r-- | lib/Makemodule.am | 1 | ||||
| -rw-r--r-- | lib/util/read_data_at.c | 34 |
3 files changed, 41 insertions, 0 deletions
diff --git a/include/util.h b/include/util.h index 8b79c30..0c36160 100644 --- a/include/util.h +++ b/include/util.h @@ -40,6 +40,12 @@ int write_data(const char *errstr, int fd, const void *data, size_t size); int read_data(const char *errstr, int fd, void *buffer, size_t size); /* + Similar to read_data but wrapps pread() instead of read(). +*/ +int read_data_at(const char *errstr, off_t location, + int fd, void *buffer, size_t size); + +/* A common implementation of the '--version' command line flag. Prints out version information. The program name is extracted from the diff --git a/lib/Makemodule.am b/lib/Makemodule.am index ab2030c..0ea95fa 100644 --- a/lib/Makemodule.am +++ b/lib/Makemodule.am @@ -42,6 +42,7 @@ libutil_a_SOURCES += lib/util/read_data.c include/util.h libutil_a_SOURCES += lib/util/print_version.c lib/util/mkdir_p.c libutil_a_SOURCES += lib/util/str_table.c include/str_table.h libutil_a_SOURCES += lib/util/dirstack.c lib/util/padd_file.c +libutil_a_SOURCES += lib/util/read_data_at.c if WITH_GZIP libcompress_a_SOURCES += lib/comp/gzip.c diff --git a/lib/util/read_data_at.c b/lib/util/read_data_at.c new file mode 100644 index 0000000..98432d9 --- /dev/null +++ b/lib/util/read_data_at.c @@ -0,0 +1,34 @@ +/* SPDX-License-Identifier: GPL-3.0-or-later */ +#include "config.h" + +#include <unistd.h> +#include <errno.h> +#include <stdio.h> + +#include "util.h" + +int read_data_at(const char *errstr, off_t location, int fd, + void *buffer, size_t size) +{ + ssize_t ret; + + while (size > 0) { + ret = pread(fd, buffer, size, location); + if (ret < 0) { + if (errno == EINTR) + continue; + perror(errstr); + return -1; + } + if (ret == 0) { + fprintf(stderr, "%s: short read\n", errstr); + return -1; + } + + size -= ret; + buffer = (char *)buffer + ret; + location += ret; + } + + return 0; +} |