Fossil

int name_to_uuid(Blob *pName, int iErrPriority){
  int rc;
  int sz;
  sz = blob_size(pName);
  if( sz>UUID_SIZE || sz<4 || !validate16(blob_buffer(pName), sz) ){
    Stmt q;
    Blob uuid;
    static const char prefix[] = "tag:";
    static const int preflen = sizeof(prefix)-1;
    const char *zName = blob_str(pName);

    if( strncmp(zName, prefix, preflen)==0 ){
      zName += preflen;
    }

    db_prepare(&q,
      "SELECT (SELECT uuid FROM blob WHERE rid=objid)"
      "  FROM tagxref JOIN event ON rid=objid"
      " WHERE tagid=(SELECT tagid FROM tag WHERE tagname='sym-'||%Q)"
      "   AND tagtype>0"
      "   AND value IS NULL"
      " ORDER BY event.mtime DESC",
      zName
    );
    blob_zero(&uuid);
    if( db_step(&q)==SQLITE_ROW ){
      db_column_blob(&q, 0, &uuid);
    }
    db_finalize(&q);
    if( blob_size(&uuid)==0 ){
      fossil_error(iErrPriority, "not a valid object name: %s", zName);
      blob_reset(&uuid);
      return 1;
    }else{
      blob_reset(pName);
      *pName = uuid;
      return 0;
    }

  blob_zero(&uuid);
  blob_append(&uuid, zObjName, -1);
  if( name_to_uuid(&uuid, 9) ){
    return;
  }
  rid = name_to_rid(blob_str(&uuid));
  blob_zero(&ctrl);

  if( validate16(zTagname, strlen(zTagname)) ){
    fossil_fatal("invalid tag name \"%s\" - might be confused with a UUID",
                 zTagname);
  }
  zDate = db_text(0, "SELECT datetime('now')");
  zDate[10] = 'T';
  blob_appendf(&ctrl, "D %s\n", zDate);

/*
** COMMAND: tag
** Usage: %fossil tag SUBCOMMAND ...
**
** Run various subcommands to control tags and properties
**
**     %fossil tag add ?--raw? TAGNAME UUID ?VALUE?
**
**         Add a new tag or property to UUID. The tag will
**         be usable instead of a UUID in commands like
**         update and the like.
**
**     %fossil tag branch ?--raw? TAGNAME UUID ?VALUE?
**
**         Add a new tag or property to UUID and make that
**         tag propagate to all direct children.
**
**     %fossil tag delete ?--raw? TAGNAME UUID
**
**         Delete the tag TAGNAME from UUID
**
**     %fossil tag find ?--raw? TAGNAME
**
**         List all baselines that use TAGNAME
**
**     %fossil tag list ?--raw? ?UUID?
**
**         List all tags, or if UUID is supplied, list
**         all tags and their values for UUID.
**
** The option ?--raw? is to expose the internal interface 
** for tag handling. This option is not necessary for the
** normal use.
**
** If you use a tagname that might be confused with a UUID,
** you have to explicitly disambiguate it by prefixing it
** with "tag:". For instance:
**
**   fossil update cfcfcfee
**
** is not the same as:
**
**   fossil update tag:cfcfcfee
**
** The first will be taken as UUID and fossil will complain
** if no such revision was found, and the second one expect
** "cfcfcfee" to be a tag/branch name!
**
*/
void tag_cmd(void){
  int n;
  int raw = find_option("raw","",0)!=0;
  const char *prefix = raw ? "" : "sym-";
  int preflen = strlen(prefix);
  Blob tagname;

  db_find_and_open_repository(1);
  if( g.argc<3 ){
    goto tag_cmd_usage;
  }
  n = strlen(g.argv[2]);
  if( n==0 ){
    goto tag_cmd_usage;
  }

  blob_set(&tagname, prefix);

  if( strncmp(g.argv[2],"add",n)==0 ){
    char *zValue;
    if( g.argc!=5 && g.argc!=6 ){
      usage("add TAGNAME UUID ?VALUE?");
    }
    blob_append(&tagname, g.argv[3], strlen(g.argv[3]));
    zValue = g.argc==6 ? g.argv[5] : 0;
    tag_add_artifact(blob_str(&tagname), g.argv[4], zValue, 1);
  }else

  if( strncmp(g.argv[2],"branch",n)==0 ){
    char *zValue;
    if( g.argc!=5 && g.argc!=6 ){
      usage("branch TAGNAME UUID ?VALUE?");
    }
    blob_append(&tagname, g.argv[3], strlen(g.argv[3]));
    zValue = g.argc==6 ? g.argv[5] : 0;
    tag_add_artifact(blob_str(&tagname), g.argv[4], zValue, 2);
  }else

  if( strncmp(g.argv[2],"delete",n)==0 ){
    if( g.argc!=5 ){
      usage("delete TAGNAME UUID");
    }
    blob_append(&tagname, g.argv[3], strlen(g.argv[3]));
    tag_add_artifact(blob_str(&tagname), g.argv[4], 0, 0);
  }else

  if( strncmp(g.argv[2],"find",n)==0 ){
    Stmt q;
    if( g.argc!=4 ){
      usage("find TAGNAME");
    }
    blob_append(&tagname, g.argv[3], strlen(g.argv[3]));
    db_prepare(&q,
      "SELECT blob.uuid FROM tagxref, blob"
      " WHERE tagid=(SELECT tagid FROM tag WHERE tagname=%B)"
      "   AND blob.rid=tagxref.rid", &tagname
    );
    while( db_step(&q)==SQLITE_ROW ){
      printf("%s\n", db_column_text(&q, 0));
    }
    db_finalize(&q);
  }else

  if( strncmp(g.argv[2],"list",n)==0 ){
    Stmt q;
    if( g.argc==3 ){
      db_prepare(&q, 
        "SELECT tagname"
        "  FROM tag"
        " WHERE EXISTS(SELECT 1 FROM tagxref"
        "               WHERE tagid=tag.tagid"
        "                 AND tagtype>0)"
        " ORDER BY tagname"
      );
      while( db_step(&q)==SQLITE_ROW ){
        const char *name = db_column_text(&q, 0);
        if( raw || strncmp(name, prefix, preflen)==0 ){
          printf("%s\n", name+preflen);
        }
      }
      db_finalize(&q);
    }else if( g.argc==4 ){
      int rid = name_to_rid(g.argv[3]);
      db_prepare(&q,
        "SELECT tagname, value"
        "  FROM tagxref, tag"
        " WHERE tagxref.rid=%d AND tagxref.tagid=tag.tagid"
        "   AND tagtype>0"
        " ORDER BY tagname",
        rid
      );
      while( db_step(&q)==SQLITE_ROW ){
        const char *zName = db_column_text(&q, 0);
        const char *zValue = db_column_text(&q, 1);
        if( zValue ){
          if( raw || strncmp(zName, prefix, preflen)==0 ){
            printf("%s=%s\n", zName+preflen, zValue);
          }
        }else{
          if( raw || strncmp(zName, prefix, preflen)==0 ){
            printf("%s\n", zName+preflen);
          }
        }
      }
      db_finalize(&q);
    }else{
      usage("tag list ?UUID?");
    }
  }else
  {
    goto tag_cmd_usage;
  }

  /* Cleanup */
  blob_reset(&tagname);
  return;

tag_cmd_usage:
  usage("add|branch|delete|find|list ...");
}