POSIX: make readv() and writev() conform to IEEE Std 1003.1-2001

The standardized version of readv() and writev() take an int as the third
parameter. Arguably a size_t makes more sense, but the standardization bodies
decided otherwise.

The non-standard functions of readv_pos() and writev_pos() have been updated
for consistency. The corresponding _kern_readv() and _kern_writev() internal
functions continue to take the size_t parameter.

The ABI will not change, even though on 64 bit machines the size of the count
parameter will change from 8 to 4 bytes.

The actual use will be slightly different. Like with the size_t argument type,
it will not be possible to give a count lower than 0. If the value is less than
0, then the B_BAD_VALUE/EINVAL error will be set.

Change-Id: I949c8ed67dbc0b4e209768cbdee554c929fc242e
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3770
Reviewed-by: Jérôme Duval <[email protected]>

headers/posix/sys/uio.h

@@ -19,10 +19,10 @@ typedef struct iovec {
 extern "C" {
 #endif
 
-ssize_t readv(int fd, const struct iovec *vector, size_t count);
+ssize_t readv(int fd, const struct iovec *vector, int count);
-ssize_t readv_pos(int fd, off_t pos, const struct iovec *vec, size_t count);
+ssize_t readv_pos(int fd, off_t pos, const struct iovec *vec, int count);
-ssize_t writev(int fd, const struct iovec *vector, size_t count);
+ssize_t writev(int fd, const struct iovec *vector, int count);
-ssize_t writev_pos(int fd, off_t pos, const struct iovec *vec, size_t count);
+ssize_t writev_pos(int fd, off_t pos, const struct iovec *vec, int count);
 
 #ifdef __cplusplus
 }

headers/private/fs_shell/fssh_uio.h

@@ -20,13 +20,13 @@ extern "C" {
 #endif
 
 fssh_ssize_t fssh_readv(int fd, const struct fssh_iovec *vector,
-					fssh_size_t count);
+					int count);
 fssh_ssize_t fssh_readv_pos(int fd, fssh_off_t pos, const struct
-					fssh_iovec *vec, fssh_size_t count);
+					fssh_iovec *vec, int count);
 fssh_ssize_t fssh_writev(int fd, const struct fssh_iovec *vector,
-					fssh_size_t count);
+					int count);
 fssh_ssize_t fssh_writev_pos(int fd, fssh_off_t pos,
-					const struct fssh_iovec *vec, fssh_size_t count);
+					const struct fssh_iovec *vec, int count);
 
 #ifdef __cplusplus
 }

src/system/boot/loader/vfs.cpp

@@ -986,11 +986,14 @@ write(int fd, const void *buffer, size_t bufferSize)
 
 
 ssize_t
-writev(int fd, const struct iovec* vecs, size_t count)
+writev(int fd, const struct iovec* vecs, int count)
 {
 	size_t totalWritten = 0;
 
-	for (size_t i = 0; i < count; i++) {
+	if (count < 0)
+		RETURN_AND_SET_ERRNO(B_BAD_VALUE);
+
+	for (int i = 0; i < count; i++) {
 		ssize_t written = write(fd, vecs[i].iov_base, vecs[i].iov_len);
 		if (written < 0)
 			return totalWritten == 0 ? written : totalWritten;

src/system/libroot/posix/sys/uio.c

@@ -14,19 +14,24 @@
 
 
 ssize_t
-readv(int fd, const struct iovec *vecs, size_t count)
+readv(int fd, const struct iovec *vecs, int count)
 {
-	ssize_t bytes = _kern_readv(fd, -1, vecs, count);
+	ssize_t bytes;
+	if (count < 0) {
+		__set_errno(B_BAD_VALUE);
+		return -1;
+	}
+	bytes = _kern_readv(fd, -1, vecs, count);
 
 	RETURN_AND_SET_ERRNO(bytes);
 }
 
 
 ssize_t
-readv_pos(int fd, off_t pos, const struct iovec *vecs, size_t count)
+readv_pos(int fd, off_t pos, const struct iovec *vecs, int count)
 {
 	ssize_t bytes;
-	if (pos < 0) {
+	if (pos < 0 || count < 0) {
 		__set_errno(B_BAD_VALUE);
 		return -1;
 	}
@@ -37,19 +42,24 @@ readv_pos(int fd, off_t pos, const struct iovec *vecs, size_t count)
 
 
 ssize_t
-writev(int fd, const struct iovec *vecs, size_t count)
+writev(int fd, const struct iovec *vecs, int count)
 {
-	ssize_t bytes = _kern_writev(fd, -1, vecs, count);
+	ssize_t bytes;
+	if (count < 0) {
+		__set_errno(B_BAD_VALUE);
+		return -1;
+	}
+	bytes = _kern_writev(fd, -1, vecs, count);
 
 	RETURN_AND_SET_ERRNO(bytes);
 }
 
 
 ssize_t
-writev_pos(int fd, off_t pos, const struct iovec *vecs, size_t count)
+writev_pos(int fd, off_t pos, const struct iovec *vecs, int count)
 {
 	ssize_t bytes;
-	if (pos < 0) {
+	if (pos < 0 || count < 0) {
 		__set_errno(B_BAD_VALUE);
 		return -1;
 	}

src/tools/fs_shell/uio.cpp

@@ -19,19 +19,19 @@
 #include "partition_support.h"
 
 
-static const fssh_size_t kMaxIOVecs = 1024;
+static const int kMaxIOVecs = 1024;
 
 
 bool
-prepare_iovecs(const struct fssh_iovec *vecs, fssh_size_t count,
+prepare_iovecs(const struct fssh_iovec *vecs, int count,
 	struct iovec* systemVecs)
 {
-	if (count > kMaxIOVecs) {
+	if (count < 0 || count > kMaxIOVecs) {
 		errno = B_BAD_VALUE;
 		return false;
 	}
 
-	for (fssh_size_t i = 0; i < count; i++) {
+	for (int i = 0; i < count; i++) {
 		systemVecs[i].iov_base = vecs[i].iov_base;
 		systemVecs[i].iov_len = vecs[i].iov_len;
 	}
@@ -41,7 +41,7 @@ prepare_iovecs(const struct fssh_iovec *vecs, fssh_size_t count,
 
 
 fssh_ssize_t
-fssh_readv(int fd, const struct fssh_iovec *vector, fssh_size_t count)
+fssh_readv(int fd, const struct fssh_iovec *vector, int count)
 {
 	struct iovec systemVecs[kMaxIOVecs];
 	if (!prepare_iovecs(vector, count, systemVecs))
@@ -62,7 +62,7 @@ fssh_readv(int fd, const struct fssh_iovec *vector, fssh_size_t count)
 
 fssh_ssize_t
 fssh_readv_pos(int fd, fssh_off_t pos, const struct fssh_iovec *vec,
-	fssh_size_t count)
+	int count)
 {
 	struct iovec systemVecs[kMaxIOVecs];
 	if (!prepare_iovecs(vec, count, systemVecs))
@@ -77,7 +77,7 @@ fssh_readv_pos(int fd, fssh_off_t pos, const struct fssh_iovec *vec,
 
 
 fssh_ssize_t
-fssh_writev(int fd, const struct fssh_iovec *vector, fssh_size_t count)
+fssh_writev(int fd, const struct fssh_iovec *vector, int count)
 {
 	struct iovec systemVecs[kMaxIOVecs];
 	if (!prepare_iovecs(vector, count, systemVecs))
@@ -98,7 +98,7 @@ fssh_writev(int fd, const struct fssh_iovec *vector, fssh_size_t count)
 
 fssh_ssize_t
 fssh_writev_pos(int fd, fssh_off_t pos, const struct fssh_iovec *vec,
-				fssh_size_t count)
+				int count)
 {
 	struct iovec systemVecs[kMaxIOVecs];
 	if (!prepare_iovecs(vec, count, systemVecs))