[Qemu-devel] [PATCH v5] qemu-io: add pattern file for write command

[Qemu-devel] [PATCH v5] qemu-io: add pattern file for write command

[Denis Plotnikov]

The patch allows to provide a pattern file for write
command. There was no similar ability before.

Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
---
v5:
  * file name initiated with null to make compilers happy

v4:
  * missing signed-off clause added
 
v3:
  * missing file closing added
  * exclusive flags processing changed
  * buffer void* converted to char* to fix pointer arithmetics
  * file reading error processing added
---
 qemu-io-cmds.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 75 insertions(+), 6 deletions(-)

diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
index 09750a23ce..5779c3b77d 100644
--- a/qemu-io-cmds.c
+++ b/qemu-io-cmds.c
@@ -21,6 +21,7 @@
 #include "qemu/option.h"
 #include "qemu/timer.h"
 #include "qemu/cutils.h"
+#include "string.h"
 
 #define CMD_NOFILE_OK   0x01
 
@@ -343,6 +344,61 @@ static void *qemu_io_alloc(BlockBackend *blk, size_t len, int pattern)
     return buf;
 }
 
+static void *qemu_io_alloc_from_file(BlockBackend *blk, size_t len,
+                                     char *file_name)
+{
+    char *buf, *buf_pos;
+    FILE *f = fopen(file_name, "r");
+    int l;
+
+    if (!f) {
+        printf("'%s': %s\n", file_name, strerror(errno));
+        return NULL;
+    }
+
+    if (qemuio_misalign) {
+        len += MISALIGN_OFFSET;
+    }
+    buf = blk_blockalign(blk, len);
+    memset(buf, 0, len);
+
+    buf_pos = buf;
+
+    while (len > 0) {
+        l = fread(buf_pos, sizeof(char), len, f);
+
+        if (feof(f)) {
+            rewind(f);
+        }
+
+        if (ferror(f)) {
+            printf("'%s': %s\n", file_name, strerror(errno));
+            goto error;
+        }
+
+        if (l == 0) {
+            printf("'%s' is empty\n", file_name);
+            goto error;
+        }
+
+        len -= l;
+        buf_pos += l;
+    }
+
+    if (qemuio_misalign) {
+        buf += MISALIGN_OFFSET;
+    }
+
+    goto out;
+
+error:
+    qemu_vfree(buf);
+    buf = NULL;
+out:
+    fclose(f);
+    return buf;
+}
+
 static void qemu_io_free(void *p)
 {
     if (qemuio_misalign) {
@@ -965,7 +1021,7 @@ static const cmdinfo_t write_cmd = {
     .perm       = BLK_PERM_WRITE,
     .argmin     = 2,
     .argmax     = -1,
-    .args       = "[-bcCfnquz] [-P pattern] off len",
+    .args       = "[-bcCfnquz] [-P pattern | -s source_file] off len",
     .oneline    = "writes a number of bytes at a specified offset",
     .help       = write_help,
 };
@@ -974,7 +1030,7 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
 {
     struct timeval t1, t2;
     bool Cflag = false, qflag = false, bflag = false;
-    bool Pflag = false, zflag = false, cflag = false;
+    bool Pflag = false, zflag = false, cflag = false, sflag = false;
     int flags = 0;
     int c, cnt, ret;
     char *buf = NULL;
@@ -983,8 +1039,9 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
     /* Some compilers get confused and warn if this is not initialized.  */
     int64_t total = 0;
     int pattern = 0xcd;
+    char *file_name = NULL;
 
-    while ((c = getopt(argc, argv, "bcCfnpP:quz")) != -1) {
+    while ((c = getopt(argc, argv, "bcCfnpP:quzs:")) != -1) {
         switch (c) {
         case 'b':
             bflag = true;
@@ -1020,6 +1077,10 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
         case 'z':
             zflag = true;
             break;
+        case 's':
+            sflag = true;
+            file_name = g_strdup(optarg);
+            break;
         default:
             qemuio_command_usage(&write_cmd);
             return -EINVAL;
@@ -1051,8 +1112,9 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
         return -EINVAL;
     }
 
-    if (zflag && Pflag) {
-        printf("-z and -P cannot be specified at the same time\n");
+    if ((int)zflag + (int)Pflag + (int)sflag > 1) {
+        printf("Only one of -z, -P, and -s"
+               "can be specified at the same time\n");
         return -EINVAL;
     }
 
@@ -1088,7 +1150,14 @@ static int write_f(BlockBackend *blk, int argc, char **argv)
     }
 
     if (!zflag) {
-        buf = qemu_io_alloc(blk, count, pattern);
+        if (sflag) {
+            buf = qemu_io_alloc_from_file(blk, count, file_name);
+            if (!buf) {
+                return -EINVAL;
+            }
+        } else {
+            buf = qemu_io_alloc(blk, count, pattern);
+        }
     }
 
     gettimeofday(&t1, NULL);
-- 
2.17.0

Re: [Qemu-devel] [PATCH v5] qemu-io: add pattern file for write command

[Eric Blake]

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On 5/31/19 2:46 AM, Denis Plotnikov wrote:
> The patch allows to provide a pattern file for write
> command. There was no similar ability before.
> 
> Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
> ---
> v5:
>   * file name initiated with null to make compilers happy
> 

> +static void *qemu_io_alloc_from_file(BlockBackend *blk, size_t len,
> +                                     char *file_name)
> +{
> +    char *buf, *buf_pos;
> +    FILE *f = fopen(file_name, "r");
> +    int l;
> +
> +    if (!f) {
> +        printf("'%s': %s\n", file_name, strerror(errno));
> +        return NULL;
> +    }
> +
> +    if (qemuio_misalign) {
> +        len += MISALIGN_OFFSET;
> +    }
> +    buf = blk_blockalign(blk, len);
> +    memset(buf, 0, len);
> +
> +    buf_pos = buf;
> +
> +    while (len > 0) {
> +        l = fread(buf_pos, sizeof(char), len, f);
> +
> +        if (feof(f)) {
> +            rewind(f);
> +        }

Why are we reading the file more than once? Once we've read it once,
it's more efficient to switch to a loop that memcpy()s the prefix into
the rest of the buffer, rather than to perform repeated I/O.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org


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Re: [Qemu-devel] [PATCH v5] qemu-io: add pattern file for write command

[Denis Plotnikov]

On 31.05.2019 18:13, Eric Blake wrote:
> On 5/31/19 2:46 AM, Denis Plotnikov wrote:
>> The patch allows to provide a pattern file for write
>> command. There was no similar ability before.
>>
>> Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
>> ---
>> v5:
>>    * file name initiated with null to make compilers happy
>>
> 
>> +static void *qemu_io_alloc_from_file(BlockBackend *blk, size_t len,
>> +                                     char *file_name)
>> +{
>> +    char *buf, *buf_pos;
>> +    FILE *f = fopen(file_name, "r");
>> +    int l;
>> +
>> +    if (!f) {
>> +        printf("'%s': %s\n", file_name, strerror(errno));
>> +        return NULL;
>> +    }
>> +
>> +    if (qemuio_misalign) {
>> +        len += MISALIGN_OFFSET;
>> +    }
>> +    buf = blk_blockalign(blk, len);
>> +    memset(buf, 0, len);
>> +
>> +    buf_pos = buf;
>> +
>> +    while (len > 0) {
>> +        l = fread(buf_pos, sizeof(char), len, f);
>> +
>> +        if (feof(f)) {
>> +            rewind(f);
>> +        }
> 
> Why are we reading the file more than once? Once we've read it once,
> it's more efficient to switch to a loop that memcpy()s the prefix into
> the rest of the buffer, rather than to perform repeated I/O.
> 
Yes, it is. Will change it.

Denis