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Re: [Xen-devel] [PATCH 2 of 2] xl: Make clear distinction between "filename" and "data source"



On 15/05/12 16:29, Ian Campbell wrote:
On Tue, 2012-05-15 at 15:51 +0100, George Dunlap wrote:
Many places in xl there's a variable or element named "filename" which
does not contain a filename, but the source of the data for reporting
purposes.  Worse, there are variables which are sometimes actually
used or interpreted as a filename depending on what other variables
are set.  This makes it difficult to tell when a string is purely
cosmetic, and when another bit of code may actually attempt to call
"open" with the string.

This patch makes a consistent distinction between "filename" (which
always refers to the name of an actual file, and may be interpreted as
such at some point) and "source" (which may be a filename, or may be
another data source such as a migration stream or saved data).

This does add some variables and reshuffle where assignments happen;
most notably, the "restore_filename" element of struct domain_create
is now only set when restoring from a file.

But at a high level, there should be no funcitonal changes.

Signed-off-by: George Dunlap<george.dunlap@xxxxxxxxxxxxx>
I've committed this (and the preceding patch), there were a few
conflicts with Goncalo's vncviewer patch (a new param to
parse_config_data). Please do check I've done the right thing.
Looks like you missed one s/config_file/config_source/ for parse_config_data; I'll follow-up with a patch.

 -George

diff -r 750b4dbab4b5 -r d555dd6614af tools/libxl/libxl_utils.c
--- a/tools/libxl/libxl_utils.c Tue May 15 15:45:55 2012 +0100
+++ b/tools/libxl/libxl_utils.c Tue May 15 15:51:25 2012 +0100
@@ -334,7 +334,7 @@ int libxl_read_file_contents(libxl_ctx *
                                                                            \
    int libxl_##rw##_exactly(libxl_ctx *ctx, int fd,                 \
                             constdata void *data, ssize_t sz,              \
-                           const char *filename, const char *what) {      \
+                           const char *source, const char *what) {      \
        ssize_t got;                                                        \
                                                                            \
        while (sz>  0) {                                                    \
@@ -343,7 +343,7 @@ int libxl_read_file_contents(libxl_ctx *
                if (errno == EINTR) continue;                               \
                if (!ctx) return errno;                                     \
                LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "failed to " #rw " 
%s%s%s", \
-                           what?what:"", what?" from ":"", filename);     \
+                           what?what:"", what?" from ":"", source);       \
                return errno;                                               \
            }                                                               \
            if (got == 0) {                                                 \
@@ -352,7 +352,7 @@ int libxl_read_file_contents(libxl_ctx *
                       zero_is_eof                                          \
                       ? "file/stream truncated reading %s%s%s"             \
                       : "file/stream write returned 0! writing %s%s%s",    \
-                     what?what:"", what?" from ":"", filename);           \
+                     what?what:"", what?" from ":"", source);             \
                return EPROTO;                                              \
            }                                                               \
            sz -= got;                                                      \
diff -r 750b4dbab4b5 -r d555dd6614af tools/libxl/xl_cmdimpl.c
--- a/tools/libxl/xl_cmdimpl.c  Tue May 15 15:45:55 2012 +0100
+++ b/tools/libxl/xl_cmdimpl.c  Tue May 15 15:51:25 2012 +0100
@@ -520,9 +520,9 @@ vcpp_out:
      return rc;
  }

-static void parse_config_data(const char *configfile_filename_report,
-                              const char *configfile_data,
-                              int configfile_len,
+static void parse_config_data(const char *config_source,
+                              const char *config_data,
+                              int config_len,
                                libxl_domain_config *d_config)
  {
      const char *buf;
@@ -537,15 +537,15 @@ static void parse_config_data(const char
      libxl_domain_create_info *c_info =&d_config->c_info;
      libxl_domain_build_info *b_info =&d_config->b_info;

-    config= xlu_cfg_init(stderr, configfile_filename_report);
+    config= xlu_cfg_init(stderr, config_source);
      if (!config) {
          fprintf(stderr, "Failed to allocate for configuration\n");
          exit(1);
      }

-    e= xlu_cfg_readdata(config, configfile_data, configfile_len);
+    e= xlu_cfg_readdata(config, config_data, config_len);
      if (e) {
-        fprintf(stderr, "Failed to parse config file: %s\n", strerror(e));
+        fprintf(stderr, "Failed to parse config: %s\n", strerror(e));
          exit(1);
      }

@@ -1524,6 +1524,8 @@ static int create_domain(struct domain_c
      const char *config_file = dom_info->config_file;
      const char *extra_config = dom_info->extra_config;
      const char *restore_file = dom_info->restore_file;
+    const char *config_source = NULL;
+    const char *restore_source = NULL;
      int migrate_fd = dom_info->migrate_fd;

      int i;
@@ -1539,24 +1541,28 @@ static int create_domain(struct domain_c
      pid_t child_console_pid = -1;
      struct save_file_header hdr;

+    int restoring = (restore_file || (migrate_fd>= 0));
+
      libxl_domain_config_init(&d_config);

-    if (restore_file) {
+    if (restoring) {
          uint8_t *optdata_begin = 0;
          const uint8_t *optdata_here = 0;
          union { uint32_t u32; char b[4]; } u32buf;
          uint32_t badflags;

          if (migrate_fd>= 0) {
+            restore_source = "<incoming migration stream>";
              restore_fd = migrate_fd;
          } else {
+            restore_source = restore_file;
              restore_fd = open(restore_file, O_RDONLY);
              rc = libxl_fd_set_cloexec(ctx, restore_fd, 1);
              if (rc) return rc;
          }

          CHK_ERRNO( libxl_read_exactly(ctx, restore_fd,&hdr,
-                   sizeof(hdr), restore_file, "header") );
+                   sizeof(hdr), restore_source, "header") );
          if (memcmp(hdr.magic, savefileheader_magic, sizeof(hdr.magic))) {
              fprintf(stderr, "File has wrong magic number -"
                      " corrupt or for a different tool?\n");
@@ -1569,7 +1575,7 @@ static int create_domain(struct domain_c
          fprintf(stderr, "Loading new save file %s"
                  " (new xl fmt info"
                  " 0x%"PRIx32"/0x%"PRIx32"/%"PRIu32")\n",
-                restore_file, hdr.mandatory_flags, hdr.optional_flags,
+                restore_source, hdr.mandatory_flags, hdr.optional_flags,
                  hdr.optional_data_len);

          badflags = hdr.mandatory_flags&  ~( 0 /* none understood yet */ );
@@ -1582,7 +1588,7 @@ static int create_domain(struct domain_c
          if (hdr.optional_data_len) {
              optdata_begin = xmalloc(hdr.optional_data_len);
              CHK_ERRNO( libxl_read_exactly(ctx, restore_fd, optdata_begin,
-                   hdr.optional_data_len, restore_file, "optdata") );
+                   hdr.optional_data_len, restore_source, "optdata") );
          }

  #define OPTDATA_LEFT  (hdr.optional_data_len - (optdata_here - optdata_begin))
@@ -1617,7 +1623,7 @@ static int create_domain(struct domain_c
                                         &config_data,&config_len);
          if (ret) { fprintf(stderr, "Failed to read config file: %s: %s\n",
                             config_file, strerror(errno)); return ERROR_FAIL; }
-        if (!restore_file&&  extra_config&&  strlen(extra_config)) {
+        if (!restoring&&  extra_config&&  strlen(extra_config)) {
              if (config_len>  INT_MAX - (strlen(extra_config) + 2 + 1)) {
                  fprintf(stderr, "Failed to attach extra configration\n");
                  return ERROR_FAIL;
@@ -1632,19 +1638,20 @@ static int create_domain(struct domain_c
              config_len += sprintf(config_data + config_len, "\n%s\n",
                  extra_config);
          }
+        config_source=config_file;
      } else {
          if (!config_data) {
              fprintf(stderr, "Config file not specified and"
                      " none in save file\n");
              return ERROR_INVAL;
          }
-        config_file = "<saved>";
+        config_source = "<saved>";
      }

      if (!dom_info->quiet)
-        printf("Parsing config file %s\n", config_file);
-
-    parse_config_data(config_file, config_data, config_len,&d_config);
+        printf("Parsing config from %s\n", config_source);
+
+    parse_config_data(config_source, config_data, config_len,&d_config);

      if (migrate_fd>= 0) {
          if (d_config.c_info.name) {
@@ -1698,7 +1705,7 @@ start:
          autoconnect_console_how = 0;
      }

-    if ( restore_file ) {
+    if ( restoring ) {
          ret = libxl_domain_create_restore(ctx,&d_config,
                                            &domid, restore_fd,
                                            0, autoconnect_console_how);
@@ -2559,7 +2566,7 @@ static void list_domains_details(const l
  {
      libxl_domain_config d_config;

-    char *config_file;
+    char *config_source;
      uint8_t *data;
      int i, len, rc;

@@ -2570,13 +2577,13 @@ static void list_domains_details(const l
          rc = libxl_userdata_retrieve(ctx, info[i].domid, "xl",&data,&len);
          if (rc)
              continue;
-        CHK_ERRNO(asprintf(&config_file, "<domid %d data>", info[i].domid));
+        CHK_ERRNO(asprintf(&config_source, "<domid %d data>", info[i].domid));
          libxl_domain_config_init(&d_config);
-        parse_config_data(config_file, (char *)data, len,&d_config);
+        parse_config_data(config_source, (char *)data, len,&d_config);
          printf_info(default_output_format, info[i].domid,&d_config);
          libxl_domain_config_dispose(&d_config);
          free(data);
-        free(config_file);
+        free(config_source);
      }
  }

@@ -2679,7 +2686,7 @@ static void save_domain_core_begin(const
      }
  }

-static void save_domain_core_writeconfig(int fd, const char *filename,
+static void save_domain_core_writeconfig(int fd, const char *source,
                                    const uint8_t *config_data, int config_len)
  {
      struct save_file_header hdr;
@@ -2708,13 +2715,13 @@ static void save_domain_core_writeconfig
      /* that's the optional data */

      CHK_ERRNO( libxl_write_exactly(ctx, fd,
-&hdr, sizeof(hdr), filename, "header") );
+&hdr, sizeof(hdr), source, "header") );
      CHK_ERRNO( libxl_write_exactly(ctx, fd,
-        optdata_begin, hdr.optional_data_len, filename, "header") );
+        optdata_begin, hdr.optional_data_len, source, "header") );

      fprintf(stderr, "Saving to %s new xl format (info"
              " 0x%"PRIx32"/0x%"PRIx32"/%"PRIu32")\n",
-            filename, hdr.mandatory_flags, hdr.optional_flags,
+            source, hdr.mandatory_flags, hdr.optional_flags,
              hdr.optional_data_len);
  }

@@ -3039,7 +3046,6 @@ static void migrate_receive(int debug, i
      dom_info.daemonize = daemonize;
      dom_info.monitor = monitor;
      dom_info.paused = 1;
-    dom_info.restore_file = "incoming migration stream";
      dom_info.migrate_fd = 0; /* stdin */
      dom_info.migration_domname_r =&migration_domname;
      dom_info.incr_generationid = 0;

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