[Libguestfs] [PATCH 2/4] New API: pread-device, partial read for devices.
Richard W.M. Jones
rjones at redhat.com
Mon Sep 27 16:16:14 UTC 2010
--
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>From 7e4bf29fdf3067f3e83cd818a79ee522ae28e7ef Mon Sep 17 00:00:00 2001
From: Richard W.M. Jones <rjones at redhat.com>
Date: Mon, 27 Sep 2010 12:00:10 +0100
Subject: [PATCH 2/4] New API: pread-device, partial read for devices.
---
daemon/file.c | 53 ++++++++++++++++++++++++++++-----------
generator/generator_actions.ml | 15 ++++++++++-
src/MAX_PROC_NR | 2 +-
3 files changed, 53 insertions(+), 17 deletions(-)
diff --git a/daemon/file.c b/daemon/file.c
index 5bc5f41..c16a00a 100644
--- a/daemon/file.c
+++ b/daemon/file.c
@@ -408,20 +408,22 @@ do_read_file (const char *path, size_t *size_r)
return r;
}
-char *
-do_pread (const char *path, int count, int64_t offset, size_t *size_r)
+static char *
+pread_fd (int fd, int count, int64_t offset, size_t *size_r,
+ const char *display_path)
{
- int fd;
ssize_t r;
char *buf;
if (count < 0) {
reply_with_error ("count is negative");
+ close (fd);
return NULL;
}
if (offset < 0) {
reply_with_error ("offset is negative");
+ close (fd);
return NULL;
}
@@ -431,16 +433,8 @@ do_pread (const char *path, int count, int64_t offset, size_t *size_r)
* will be caught later when we try to serialize the message.
*/
if (count >= GUESTFS_MESSAGE_MAX) {
- reply_with_error ("%s: count is too large for the protocol, use smaller reads", path);
- return NULL;
- }
-
- CHROOT_IN;
- fd = open (path, O_RDONLY);
- CHROOT_OUT;
-
- if (fd == -1) {
- reply_with_perror ("open: %s", path);
+ reply_with_error ("%s: count is too large for the protocol, use smaller reads", display_path);
+ close (fd);
return NULL;
}
@@ -453,14 +447,14 @@ do_pread (const char *path, int count, int64_t offset, size_t *size_r)
r = pread (fd, buf, count, offset);
if (r == -1) {
- reply_with_perror ("pread: %s", path);
+ reply_with_perror ("pread: %s", display_path);
close (fd);
free (buf);
return NULL;
}
if (close (fd) == -1) {
- reply_with_perror ("close: %s", path);
+ reply_with_perror ("close: %s", display_path);
close (fd);
free (buf);
return NULL;
@@ -473,6 +467,35 @@ do_pread (const char *path, int count, int64_t offset, size_t *size_r)
return buf;
}
+char *
+do_pread (const char *path, int count, int64_t offset, size_t *size_r)
+{
+ int fd;
+
+ CHROOT_IN;
+ fd = open (path, O_RDONLY);
+ CHROOT_OUT;
+
+ if (fd == -1) {
+ reply_with_perror ("open: %s", path);
+ return NULL;
+ }
+
+ return pread_fd (fd, count, offset, size_r, path);
+}
+
+char *
+do_pread_device (const char *device, int count, int64_t offset, size_t *size_r)
+{
+ int fd = open (device, O_RDONLY);
+ if (fd == -1) {
+ reply_with_perror ("open: %s", device);
+ return NULL;
+ }
+
+ return pread_fd (fd, count, offset, size_r, device);
+}
+
static int
pwrite_fd (int fd, const char *content, size_t size, int64_t offset,
const char *display_path)
diff --git a/generator/generator_actions.ml b/generator/generator_actions.ml
index e94fcbd..c9890a6 100644
--- a/generator/generator_actions.ml
+++ b/generator/generator_actions.ml
@@ -4190,7 +4190,7 @@ bytes of the file, starting at C<offset>, from file C<path>.
This may read fewer bytes than requested. For further details
see the L<pread(2)> system call.
-See also C<guestfs_pwrite>.");
+See also C<guestfs_pwrite>, C<guestfs_pread_device>.");
("part_init", (RErr, [Device "device"; String "parttype"]), 208, [],
[InitEmpty, Always, TestRun (
@@ -5183,6 +5183,19 @@ probably impossible with standard Linux kernels).
See also C<guestfs_pwrite>.");
+ ("pread_device", (RBufferOut "content", [Device "device"; Int "count"; Int64 "offset"]), 276, [ProtocolLimitWarning],
+ [InitEmpty, Always, TestOutputBuffer (
+ [["pread_device"; "/dev/sdd"; "8"; "32768"]], "\001CD001\001\000")],
+ "read part of a device",
+ "\
+This command lets you read part of a file. It reads C<count>
+bytes of C<device>, starting at C<offset>.
+
+This may read fewer bytes than requested. For further details
+see the L<pread(2)> system call.
+
+See also C<guestfs_pread>.");
+
]
let all_functions = non_daemon_functions @ daemon_functions
diff --git a/src/MAX_PROC_NR b/src/MAX_PROC_NR
index 4c738e3..15007f1 100644
--- a/src/MAX_PROC_NR
+++ b/src/MAX_PROC_NR
@@ -1 +1 @@
-275
+276
--
1.7.3
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