wrapper: introduce writev(3p) wrappers

index 16f5a63fbb..be8fa575e6 100644 --- a/wrapper.c +++ b/wrapper.c @@ -323,6 +323,47 @@ ssize_t write_in_full(int fd, const void *buf, size_t count) return total; } +ssize_t writev_in_full(int fd, struct iovec *iov, int iovcnt) +{ + ssize_t total_written = 0; + + while (iovcnt) { + ssize_t bytes_written = writev(fd, iov, iovcnt); + if (bytes_written < 0) { + if (errno == EINTR || errno == EAGAIN) + continue; + return -1; + } + if (!bytes_written) { + errno = ENOSPC; + return -1; + } + + total_written += bytes_written; + + /* + * We first need to discard any iovec entities that have been + * fully written. + */ + while (iovcnt && (size_t)bytes_written >= iov->iov_len) { + bytes_written -= iov->iov_len; + iov++; + iovcnt--; + } + + /* + * Finally, we need to adjust the last iovec in case we have + * performed a partial write. + */ + if (iovcnt && bytes_written) { + iov->iov_base = (char *) iov->iov_base + bytes_written; + iov->iov_len -= bytes_written; + } + } + + return total_written; +} + ssize_t pread_in_full(int fd, void *buf, size_t count, off_t offset) { char *p = buf;

index 15ac3bab6e..27519b32d1 100644 --- a/wrapper.h +++ b/wrapper.h @@ -47,6 +47,15 @@ ssize_t read_in_full(int fd, void *buf, size_t count); ssize_t write_in_full(int fd, const void *buf, size_t count); ssize_t pread_in_full(int fd, void *buf, size_t count, off_t offset); +/* + * Try to write all iovecs. Returns -1 in case an error occurred with a proper + * errno set, the number of bytes written otherwise. + * + * Note that the iovec will be modified as a result of this call to adjust for + * partial writes! + */ +ssize_t writev_in_full(int fd, struct iovec *iov, int iovcnt); + static inline ssize_t write_str_in_full(int fd, const char *str) { return write_in_full(fd, str, strlen(str));

index 01a9a51fa2..5f522fb728 100644 --- a/write-or-die.c +++ b/write-or-die.c @@ -96,6 +96,14 @@ void write_or_die(int fd, const void *buf, size_t count) } } +void writev_or_die(int fd, struct iovec *iov, int iovlen) +{ + if (writev_in_full(fd, iov, iovlen) < 0) { + check_pipe(errno); + die_errno("writev error"); + } +} + void fwrite_or_die(FILE *f, const void *buf, size_t count) { if (fwrite(buf, 1, count, f) != count)

index ff0408bd84..a045bdfaef 100644 --- a/write-or-die.h +++ b/write-or-die.h @@ -7,6 +7,7 @@ void fprintf_or_die(FILE *, const char *fmt, ...); void fwrite_or_die(FILE *f, const void *buf, size_t count); void fflush_or_die(FILE *f); void write_or_die(int fd, const void *buf, size_t count); +void writev_or_die(int fd, struct iovec *iov, int iovlen); /* * These values are used to help identify parts of a repository to fsync.