Add optional '-logprefix' command line option to drcov (#3510)

Adds a new command line option '-logprefix' to drcov for better control over the output file.
Updates the changelog.

api/docs/release.dox

@@ -157,6 +157,7 @@ Further non-compatibility-affecting changes include:
  - Added the type #dr_opmask_t.
  - Added the define #MCXT_NUM_OPMASK_SLOTS for the number of AVX-512 OpMask registers.
  - Renamed mcontext's ymm structure into simd.
+ - Added a new option -logprefix to drcov.
 
 **************************************************
 <hr>

clients/drcov/drcov.c

@@ -139,6 +139,9 @@ options_init(client_id_t id, int argc, const char *argv[], drcovlib_options_t *o
         else if (strcmp(token, "-logdir") == 0) {
             USAGE_CHECK((i + 1) < argc, "missing logdir path");
             ops->logdir = argv[++i];
+        } else if (strcmp(token, "-logprefix") == 0) {
+            USAGE_CHECK((i + 1) < argc, "missing logprefix string");
+            ops->logprefix = argv[++i];
         } else if (strcmp(token, "-native_until_thread") == 0) {
             USAGE_CHECK((i + 1) < argc, "missing -native_until_thread number");
             token = argv[++i];

ext/drcovlib/drcovlib.c

@@ -94,8 +94,8 @@ log_file_create_helper(void *drcontext, const char *suffix, char *buf, size_t bu
 {
     file_t log = drx_open_unique_appid_file(
         options.logdir,
-        drcontext == NULL ? dr_get_process_id() : dr_get_thread_id(drcontext), "drcov",
-        suffix,
+        drcontext == NULL ? dr_get_process_id() : dr_get_thread_id(drcontext),
+        options.logprefix, suffix,
 #ifndef WINDOWS
         DR_FILE_CLOSE_ON_FORK |
 #endif
@@ -557,6 +557,8 @@ drcovlib_init(drcovlib_options_t *ops)
         dr_snprintf(logdir, BUFFER_SIZE_ELEMENTS(logdir), ".");
     NULL_TERMINATE_BUFFER(logdir);
     options.logdir = logdir;
+    if (options.logprefix == NULL)
+        options.logprefix = "drcov";
     if (options.native_until_thread > 0)
         go_native = true;
 

ext/drcovlib/drcovlib.h

@@ -91,6 +91,11 @@ typedef struct _drcovlib_options_t {
      * overrides that default.
      */
     const char *logdir;
+    /**
+     * By default, log file names are prefixed with "drcov".  This option overrides
+     * that default.
+     */
+    const char *logprefix;
     /**
      * This is an experimental option for running natively (i.e., not under
      * DynamoRIO control) until the nth thread, where n is the value of this