scheduler: Protect MimeDatabase from parallel access (fixes #466)

If multiple create_local_bg_thread threads are spawned, they can fight
over MimeDatabase (specifically over MimeDatabase->srcs array), ending
up in SIGSEGV if one thread uses the array, but the other deletes it.

I chose to use RW locks for protecting the pointer - IMHO we benefit
from multiple threads being able to read in parallel.

diff --git a/scheduler/client.c b/scheduler/client.c
index e7e419f1b2bf6d62bf17a9aed564ecadc23bb714..fb3717a66706128c739d45cf410179ac3a12dbbc 100644 (file)
--- a/scheduler/client.c
+++ b/scheduler/client.c
@@ -1052,8 +1052,12 @@ cupsdReadClient(cupsd_client_t *con)     /* I - Client to read from */
 
             if ((filename = get_file(con, &filestats, buf, sizeof(buf))) != NULL)
             {
+             _cupsRWLockRead(&MimeDatabase->lock);
+
              type = mimeFileType(MimeDatabase, filename, NULL, NULL);
 
+             _cupsRWUnlock(&MimeDatabase->lock);
+
               cupsdLogClient(con, CUPSD_LOG_DEBUG, "filename=\"%s\", type=%s/%s", filename, type ? type->super : "", type ? type->type : "");
 
               if (is_cgi(con, filename, &filestats, type))

diff --git a/scheduler/conf.c b/scheduler/conf.c
index 535d40f0c55be8fedd7369aa7a45a5fc4d6966db..354cac6e00169b0e46383174c12d72777e572374 100644 (file)
--- a/scheduler/conf.c
+++ b/scheduler/conf.c
@@ -1560,11 +1560,14 @@ cupsdReadConfiguration(void)
 
     MimeDatabase = mimeNew();
     mimeSetErrorCallback(MimeDatabase, mime_error_cb, NULL);
+    _cupsRWInit(&MimeDatabase->lock);
 
+    _cupsRWLockWrite(&MimeDatabase->lock);
     MimeDatabase = mimeLoadTypes(MimeDatabase, mimedir);
     MimeDatabase = mimeLoadTypes(MimeDatabase, ServerRoot);
     MimeDatabase = mimeLoadFilters(MimeDatabase, mimedir, temp);
     MimeDatabase = mimeLoadFilters(MimeDatabase, ServerRoot, temp);
+    _cupsRWUnlock(&MimeDatabase->lock);
 
     if (!MimeDatabase)
     {

diff --git a/scheduler/ipp.c b/scheduler/ipp.c
index ec950557bd1db82e6228d585cf4383378c33c63b..bea2ad958400b6ec5a5c928089f6221f0a4c9b1c 100644 (file)
--- a/scheduler/ipp.c
+++ b/scheduler/ipp.c
@@ -8655,6 +8655,8 @@ print_job(cupsd_client_t  *con,           /* I - Client connection */
     strlcpy(type, "octet-stream", sizeof(type));
   }
 
+  _cupsRWLockRead(&MimeDatabase->lock);
+
   if (!strcmp(super, "application") && !strcmp(type, "octet-stream"))
   {
    /*
@@ -8680,6 +8682,8 @@ print_job(cupsd_client_t  *con,           /* I - Client connection */
   else
     filetype = mimeType(MimeDatabase, super, type);
 
+  _cupsRWUnlock(&MimeDatabase->lock);
+
   if (filetype &&
       (!format ||
        (!strcmp(super, "application") && !strcmp(type, "octet-stream"))))
@@ -9899,6 +9903,8 @@ send_document(cupsd_client_t  *con,       /* I - Client connection */
     strlcpy(type, "octet-stream", sizeof(type));
   }
 
+  _cupsRWLockRead(&MimeDatabase->lock);
+
   if (!strcmp(super, "application") && !strcmp(type, "octet-stream"))
   {
    /*
@@ -9928,6 +9934,8 @@ send_document(cupsd_client_t  *con,       /* I - Client connection */
   else
     filetype = mimeType(MimeDatabase, super, type);
 
+  _cupsRWUnlock(&MimeDatabase->lock);
+
   if (filetype)
   {
    /*
@@ -11417,6 +11425,8 @@ validate_job(cupsd_client_t  *con,      /* I - Client connection */
       return;
     }
 
+    _cupsRWLockRead(&MimeDatabase->lock);
+
     if ((strcmp(super, "application") || strcmp(type, "octet-stream")) &&
        !mimeType(MimeDatabase, super, type))
     {
@@ -11427,8 +11437,13 @@ validate_job(cupsd_client_t  *con,     /* I - Client connection */
                      format->values[0].string.text);
       ippAddString(con->response, IPP_TAG_UNSUPPORTED_GROUP, IPP_TAG_MIMETYPE,
                    "document-format", NULL, format->values[0].string.text);
+
+      _cupsRWUnlock(&MimeDatabase->lock);
+
       return;
     }
+
+    _cupsRWUnlock(&MimeDatabase->lock);
   }
 
  /*

diff --git a/scheduler/job.c b/scheduler/job.c
index 49127753142bdb4bb5d1052dabfca775d6775e26..58d1443895ac881fdcaf5229629a738e55cda8ae 100644 (file)
--- a/scheduler/job.c
+++ b/scheduler/job.c
@@ -585,6 +585,8 @@ cupsdContinueJob(cupsd_job_t *job)  /* I - Job */
     if (stat(filename, &fileinfo))
       fileinfo.st_size = 0;
 
+    _cupsRWLockWrite(&MimeDatabase->lock);
+
     if (job->retry_as_raster)
     {
      /*
@@ -619,6 +621,9 @@ cupsdContinueJob(cupsd_job_t *job)  /* I - Job */
       abort_state   = IPP_JOB_ABORTED;
 
       ippSetString(job->attrs, &job->reasons, 0, "document-unprintable-error");
+
+      _cupsRWUnlock(&MimeDatabase->lock);
+
       goto abort_job;
     }
 
@@ -705,6 +710,8 @@ cupsdContinueJob(cupsd_job_t *job)  /* I - Job */
       cupsArrayDelete(filters);
       filters = prefilters;
     }
+
+    _cupsRWUnlock(&MimeDatabase->lock);
   }
 
  /*
@@ -1916,6 +1923,8 @@ cupsdLoadJob(cupsd_job_t *job)            /* I - Job */
     * Find all the d##### files...
     */
 
+    _cupsRWLockRead(&MimeDatabase->lock);
+
     for (fileid = 1; fileid < 10000; fileid ++)
     {
       snprintf(jobfile, sizeof(jobfile), "%s/d%05d-%03d", RequestRoot,
@@ -1980,6 +1989,8 @@ cupsdLoadJob(cupsd_job_t *job)            /* I - Job */
         job->filetypes[fileid - 1] = mimeType(MimeDatabase, "application",
                                              "vnd.cups-raw");
     }
+
+    _cupsRWUnlock(&MimeDatabase->lock);
   }
 
  /*
@@ -4484,6 +4495,8 @@ load_job_cache(const char *filename)      /* I - job.cache filename */
 
       number --;
 
+      _cupsRWLockRead(&MimeDatabase->lock);
+
       job->compressions[number] = compression;
       job->filetypes[number]    = mimeType(MimeDatabase, super, type);
 
@@ -4510,6 +4523,8 @@ load_job_cache(const char *filename)      /* I - job.cache filename */
          job->filetypes[number] = mimeType(MimeDatabase, "application",
                                            "vnd.cups-raw");
       }
+
+      _cupsRWUnlock(&MimeDatabase->lock);
     }
     else
       cupsdLogMessage(CUPSD_LOG_ERROR, "Unknown %s directive on line %d of %s.", line, linenum, filename);

diff --git a/scheduler/mime.h b/scheduler/mime.h
index 7e43ac397c7a5fd36284333efc8cec576aa63554..ea71415b06fe20cae10ee8e0c4f4d74e38e4e72d 100644 (file)
--- a/scheduler/mime.h
+++ b/scheduler/mime.h
@@ -13,6 +13,7 @@
 #  include <cups/array.h>
 #  include <cups/ipp.h>
 #  include <cups/file.h>
+#  include <cups/thread-private.h>
 #  include <regex.h>
 
 
@@ -106,6 +107,7 @@ typedef struct _mime_s                      /**** MIME Database ****/
   cups_array_t         *srcs;          /* Filters sorted by source type */
   mime_error_cb_t      error_cb;       /* Error message callback */
   void                 *error_ctx;     /* Pointer for callback */
+  _cups_rwlock_t       lock;   /* Read/write lock for guarding data for background updates */
 } mime_t;
 
 

diff --git a/scheduler/printers.c b/scheduler/printers.c
index 4efa613f3f79c69c06063fef97c97769c4a68b8d..11dd4b8e1bede354ea1154466106adfffc9ddbca 100644 (file)
--- a/scheduler/printers.c
+++ b/scheduler/printers.c
@@ -97,8 +97,13 @@ cupsdAddPrinter(const char *name)    /* I - Name of printer */
   p->state_time  = time(NULL);
   p->accepting   = 0;
   p->shared      = DefaultShared;
+
+  _cupsRWLockWrite(&MimeDatabase->lock);
+
   p->filetype    = mimeAddType(MimeDatabase, "printer", name);
 
+  _cupsRWUnlock(&MimeDatabase->lock);
+
   cupsdSetString(&p->job_sheets[0], "none");
   cupsdSetString(&p->job_sheets[1], "none");
 
@@ -815,6 +820,8 @@ cupsdDeletePrinter(
   if (p->printers != NULL)
     free(p->printers);
 
+  _cupsRWLockWrite(&MimeDatabase->lock);
+
   delete_printer_filters(p);
 
   for (i = 0; i < p->num_reasons; i ++)
@@ -828,6 +835,8 @@ cupsdDeletePrinter(
   mimeDeleteType(MimeDatabase, p->filetype);
   mimeDeleteType(MimeDatabase, p->prefiltertype);
 
+  _cupsRWUnlock(&MimeDatabase->lock);
+
   cupsdFreeStrings(&(p->users));
   cupsdFreeQuotas(p);
 
@@ -1470,6 +1479,8 @@ cupsdRenamePrinter(
   * Rename the printer type...
   */
 
+  _cupsRWLockWrite(&MimeDatabase->lock);
+
   mimeDeleteType(MimeDatabase, p->filetype);
   p->filetype = mimeAddType(MimeDatabase, "printer", name);
 
@@ -1479,6 +1490,8 @@ cupsdRenamePrinter(
     p->prefiltertype = mimeAddType(MimeDatabase, "prefilter", name);
   }
 
+  _cupsRWUnlock(&MimeDatabase->lock);
+
  /*
   * Rename the printer...
   */
@@ -2295,6 +2308,7 @@ cupsdSetPrinterAttrs(cupsd_printer_t *p)/* I - Printer to setup */
     cupsdCreateCommonData();
 
   _cupsRWLockWrite(&p->lock);
+  _cupsRWLockWrite(&MimeDatabase->lock);
 
  /*
   * Clear out old filters, if any...
@@ -2615,6 +2629,8 @@ cupsdSetPrinterAttrs(cupsd_printer_t *p)/* I - Printer to setup */
 
   add_printer_formats(p);
 
+  _cupsRWUnlock(&MimeDatabase->lock);
+
  /*
   * Add name-default attributes...
   */