Attached is a patch to refactor xl disk configuration option parsing. Please
let me know if there are further comments/issues to fix.
Signed-off-by: Kamala Narasimhan <kamala.narasimhan@xxxxxxxxxx>
Kamala
diff -u -r libxl-interface-changes/xl_cmdimpl.c libxl/xl_cmdimpl.c
--- libxl-interface-changes/xl_cmdimpl.c 2011-02-07 12:03:37.000000000
-0500
+++ libxl/xl_cmdimpl.c 2011-02-07 14:58:39.000000000 -0500
@@ -438,143 +438,184 @@
return 0;
}
-#define DSTATE_INITIAL 0
-#define DSTATE_TAP 1
-#define DSTATE_PHYSPATH 2
-#define DSTATE_VIRTPATH 3
-#define DSTATE_VIRTTYPE 4
-#define DSTATE_RW 5
-#define DSTATE_TERMINAL 6
+#define DSTATE_INITIAL 0
+#define DSTATE_ATTRIB_PARSED 1
+#define DSTATE_VDEV_PARSED 2
+static int parse_disk_attrib(libxl_device_disk *disk, char *attrib)
+{
+ if ( attrib[0] == 'w' )
+ disk->readwrite = 1;
+ else if ( attrib[0] != 'r' ) {
+ LOG("Required access rights attribute is missing or incorrect in "
+ "disk configuration option %s", attrib);
+ return ERROR_INVAL;
+ }
+
+ return 0;
+}
+
+static int parse_disk_vdev_info(libxl_device_disk *disk, char *vdev_info)
+{
+ char *vdev, *type;
+
+ type = strchr(vdev_info, ':');
+ if ( type ) {
+ *type = '\0';
+ type++;
+ if ( !strncmp(type, "cdrom", sizeof("cdrom")-1) ) {
+ disk->is_cdrom = 1;
+ disk->unpluggable = 1;
+ }
+ else {
+ LOG("Invalid vdev type %s specified in disk configuration option",
+ type);
+ return ERROR_INVAL;
+ }
+ }
+
+ vdev = vdev_info;
+ if ( vdev[0] == '\0' ) {
+ LOG("Mandatory attribute vdev not specified");
+ return ERROR_INVAL;
+ }
+
+ disk->vdev = strdup(vdev);
+ return 0;
+}
+
+static int parse_disk_pdev_info(libxl_device_disk *disk, char *pdev_info)
+{
+ char *pdev_type, *pdev_impl, *pdev_format, *pdev_path;
+
+ if ( pdev_info[0] == '\0' && !disk->is_cdrom ) {
+ /* pdev can be empty string only for cdrom drive with no media
inserted */
+ LOG("Required vdev info missing in disk configuration option");
+ return ERROR_INVAL;
+ }
+
+ pdev_path = strrchr(pdev_info, ':');
+ if ( !pdev_path ) {
+ disk->pdev_path = strdup(pdev_info);
+ return 0;
+ }
+
+ *pdev_path = '\0';
+ disk->pdev_path = strdup(++pdev_path);
+
+ pdev_format = strrchr(pdev_info, ':');
+ if ( !pdev_format )
+ pdev_format = pdev_info;
+ else {
+ *pdev_format = '\0';
+ pdev_format++;
+ }
+
+ if ( !strncmp(pdev_format, "raw", sizeof("raw")-1) )
+ disk->format = DISK_FORMAT_RAW;
+ else if ( !strncmp(pdev_format, "qcow", sizeof("qcow")-1) )
+ disk->format = DISK_FORMAT_QCOW;
+ else if ( !strncmp(pdev_format, "qcow2", sizeof("qcow2")-1) )
+ disk->format = DISK_FORMAT_QCOW2;
+ else if ( !strncmp(pdev_format, "vhd", sizeof("vhd")-1) )
+ disk->format = DISK_FORMAT_VHD;
+
+ if ( disk->format == DISK_FORMAT_UNKNOWN )
+ pdev_impl = pdev_format;
+ else {
+ pdev_impl = strrchr(pdev_info, ':');
+ if ( !pdev_impl )
+ return 0;
+ *pdev_impl = '\0';
+ pdev_impl++;
+ }
+
+ if ( !strncmp(pdev_impl, "aio", sizeof("aio")-1) ||
+ !strncmp(pdev_impl, "tapdisk", sizeof("tapdisk")-1) )
+ disk->backend = DISK_BACKEND_TAPDISK2;
+ else if ( !strncmp(pdev_impl, "ioemu", sizeof("ioemu")-1) )
+ disk->backend = DISK_BACKEND_QEMU;
+
+ if ( disk->backend == DISK_BACKEND_UNKNOWN )
+ pdev_type = pdev_impl;
+ else {
+ pdev_type = pdev_info;
+ if ( pdev_type[0] == '\0' )
+ return 0;
+ }
+
+ if ( !strncmp(pdev_type, "phy", sizeof("phy")-1) )
+ disk->backend = DISK_BACKEND_BLKBACK;
+ else if ( !strncmp(pdev_type, "file", sizeof("file")-1) ||
+ !strncmp(pdev_type, "tap", sizeof("tap")-1) ||
+ !strncmp(pdev_type, "tap2", sizeof("tap2")-1) )
+ disk->backend = DISK_BACKEND_TAPDISK2;
+
+ return 0;
+}
+
+/*
+ * Note: Following code calls methods each of which will parse
+ * specific chunks of the disk configuration option, the specific
+ * chunks being attribute, vdev and pdev. As with any parsing code
+ * it makes assumption about the order in which specific chunks appear
+ * in the disk configuration option string. So, please use
+ * care while modifying the code below, esp. when it comes to
+ * the order of calls.
+ */
static int parse_disk_config(libxl_device_disk *disk, char *buf2)
{
- int state = DSTATE_INITIAL;
- char *p, *end, *tok;
+ int state = DSTATE_INITIAL, ret_val;
+ char *substr = buf2;
memset(disk, 0, sizeof(*disk));
- for(tok = p = buf2, end = buf2 + strlen(buf2) + 1; p < end; p++) {
- switch(state){
- case DSTATE_INITIAL:
- if ( *p == ':' ) {
- *p = '\0';
- if ( !strcmp(tok, "phy") ) {
- state = DSTATE_PHYSPATH;
- disk->format = DISK_FORMAT_RAW;
- disk->backend = DISK_BACKEND_BLKBACK;
- }else if ( !strcmp(tok, "file") ) {
- state = DSTATE_PHYSPATH;
- disk->format = DISK_FORMAT_RAW;
- disk->backend = DISK_BACKEND_TAPDISK2;
- }else if ( !strcmp(tok, "tap") ) {
- state = DSTATE_TAP;
- }else{
- fprintf(stderr, "Unknown disk type: %s\n", tok);
- return 0;
+ for ( substr = strrchr(buf2, ',');
+ substr || (!substr && state == DSTATE_VDEV_PARSED);
+ substr = strrchr(buf2, ',') ) {
+ switch ( state ) {
+ case DSTATE_INITIAL: {
+ if ( !substr ) {
+ LOG("Invalid disk configuration option %s. Refer to the
xl disk "
+ "configuration document for further information", buf2);
+ return ERROR_INVAL;
}
- tok = p + 1;
- } else if (*p == ',') {
- state = DSTATE_VIRTPATH;
- disk->backend = DISK_FORMAT_EMPTY;
- disk->pdev_path = strdup("");
- tok = p + 1;
- }
- break;
- case DSTATE_TAP:
- if ( *p == ':' ) {
- *p = '\0';
- if ( !strcmp(tok, "aio") ) {
- disk->format = DISK_FORMAT_RAW;
- disk->backend = DISK_BACKEND_TAPDISK2;
- }else if ( !strcmp(tok, "vhd") ) {
- disk->format = DISK_FORMAT_VHD;
- disk->backend = DISK_BACKEND_TAPDISK2;
- }else if ( !strcmp(tok, "qcow") ) {
- disk->format = DISK_FORMAT_QCOW;
- disk->backend = DISK_BACKEND_QEMU;
- }else if ( !strcmp(tok, "qcow2") ) {
- disk->format = DISK_FORMAT_QCOW2;
- disk->backend = DISK_BACKEND_QEMU;
- }else {
- fprintf(stderr, "Unknown tapdisk type: %s\n", tok);
- return 0;
- }
-
- tok = p + 1;
- state = DSTATE_PHYSPATH;
- }
- break;
- case DSTATE_PHYSPATH:
- if ( *p == ',' ) {
- int ioemu_len;
-
- *p = '\0';
- disk->pdev_path = (*tok) ? strdup(tok) : NULL;
- tok = p + 1;
-
- /* hack for ioemu disk spec */
- ioemu_len = strlen("ioemu:");
- state = DSTATE_VIRTPATH;
- if ( tok + ioemu_len < end &&
- !strncmp(tok, "ioemu:", ioemu_len)) {
- tok += ioemu_len;
- p += ioemu_len;
- }
- }
- break;
- case DSTATE_VIRTPATH:
- if ( *p == ',' || *p == ':' || *p == '\0' ) {
- switch(*p) {
- case ':':
- state = DSTATE_VIRTTYPE;
- break;
- case ',':
- state = DSTATE_RW;
- break;
- case '\0':
- state = DSTATE_TERMINAL;
- break;
- }
- if ( tok == p )
- goto out;
- *p = '\0';
- disk->vdev = (*tok) ? strdup(tok) : NULL;
- tok = p + 1;
+ *substr = '\0';
+ substr++;
+ ret_val = parse_disk_attrib(disk, substr);
+ if ( ret_val )
+ return ret_val;
+ state = DSTATE_ATTRIB_PARSED;
+ break;
}
- break;
- case DSTATE_VIRTTYPE:
- if ( *p == ',' || *p == '\0' ) {
- *p = '\0';
- if ( !strcmp(tok, "cdrom") ) {
- disk->is_cdrom = 1;
- disk->unpluggable = 1;
- }else{
- fprintf(stderr, "Unknown virtual disk type: %s\n", tok);
- return 0;
+ case DSTATE_ATTRIB_PARSED: {
+ if ( !substr ) {
+ LOG("Required vdev info missing in disk configuration
option");
+ return ERROR_INVAL;
}
- tok = p + 1;
- state = (*p == ',') ? DSTATE_RW : DSTATE_TERMINAL;
+ *substr = '\0';
+ substr++;
+ ret_val = parse_disk_vdev_info(disk, substr);
+ if ( ret_val )
+ return ret_val;
+ state = DSTATE_VDEV_PARSED;
+ break;
}
- break;
- case DSTATE_RW:
- if ( *p == '\0' ) {
- disk->readwrite = (tok[0] == 'w');
- tok = p + 1;
- state = DSTATE_TERMINAL;
+ case DSTATE_VDEV_PARSED: {
+ ret_val = parse_disk_pdev_info(disk, buf2);
+ if ( ret_val )
+ return ret_val;
+ if ( disk->format == DISK_FORMAT_UNKNOWN )
+ disk->format = DISK_FORMAT_RAW;
+ if ( disk->backend == DISK_BACKEND_UNKNOWN )
+ disk->backend = DISK_BACKEND_TAPDISK2;
+ return 0;
}
- break;
- case DSTATE_TERMINAL:
- goto out;
}
}
-out:
- if ( tok != p || state != DSTATE_TERMINAL ) {
- fprintf(stderr, "parse error in disk config near '%s'\n", tok);
- return 0;
- }
-
- return 1;
+ LOG("Disk configuration parsing failed");
+ return ERROR_INVAL;
}
static void parse_config_data(const char *configfile_filename_report,
@@ -768,7 +809,7 @@
d_config->disks = (libxl_device_disk *) realloc(d_config->disks,
sizeof (libxl_device_disk) * (d_config->num_disks + 1));
disk = d_config->disks + d_config->num_disks;
- if ( !parse_disk_config(disk, buf2) ) {
+ if ( parse_disk_config(disk, buf2) ) {
exit(1);
}
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