Support 'help' as a synonym for '?' in command line options

For command line options which permit '?' meaning 'please list the
permitted values', add support for 'help' as a synonym, by abstracting
the check out into a helper function.

This change means that in some cases where we were being lazy in
our string parsing, "?junk" will now be rejected as an invalid option
rather than being (undocumentedly) treated the same way as "?".

Update the documentation to use 'help' rather than '?', since '?'
is a shell metacharacter and thus prone to fail confusingly if there
is a single character filename in the current working directory and
the '?' has not been escaped. It's therefore better to steer users
towards 'help', though '?' is retained for backwards compatibility.

We do not, however, update the output of the system emulator's -help
(or any documentation autogenerated from the qemu-options.hx which
is the source of the -help text) because libvirt parses our -help
output and will break. At a later date when QEMU provides a better
interface so libvirt can avoid having to do this, we can update the
-help text too.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff --git a/arch_init.c b/arch_init.c
index 26f30ef987620b6ee4aaaa527f7e13907f88b504..60823baabda99ac17d73eeffd0152451f8ee14d6 100644 (file)
--- a/arch_init.c
+++ b/arch_init.c
@@ -680,7 +680,7 @@ void select_soundhw(const char *optarg)
 {
     struct soundhw *c;
 
-    if (*optarg == '?') {
+    if (is_help_option(optarg)) {
     show_valid_cards:
 
         printf("Valid sound card names (comma separated):\n");
@@ -688,7 +688,7 @@ void select_soundhw(const char *optarg)
             printf ("%-11s %s\n", c->name, c->descr);
         }
         printf("\n-soundhw all will enable all of the above\n");
-        exit(*optarg != '?');
+        exit(!is_help_option(optarg));
     }
     else {
         size_t l;

diff --git a/blockdev.c b/blockdev.c
index 3d7501565d7006ff5a510663523bbb24d29a8ebe..8669142704b9d71c459c9740559c26d91ae772a2 100644 (file)
--- a/blockdev.c
+++ b/blockdev.c
@@ -398,11 +398,11 @@ DriveInfo *drive_init(QemuOpts *opts, int default_to_scsi)
 #endif
 
     if ((buf = qemu_opt_get(opts, "format")) != NULL) {
-       if (strcmp(buf, "?") == 0) {
-           error_printf("Supported formats:");
-           bdrv_iterate_format(bdrv_format_print, NULL);
-           error_printf("\n");
-           return NULL;
+        if (is_help_option(buf)) {
+            error_printf("Supported formats:");
+            bdrv_iterate_format(bdrv_format_print, NULL);
+            error_printf("\n");
+            return NULL;
         }
         drv = bdrv_find_whitelisted_format(buf);
         if (!drv) {

diff --git a/bsd-user/main.c b/bsd-user/main.c
index cd33d655f513b2011d04b22be885bd0830052b34..095ae8eaaaecdbbbc2d435bc351cef144eafb3a9 100644 (file)
--- a/bsd-user/main.c
+++ b/bsd-user/main.c
@@ -681,7 +681,7 @@ static void usage(void)
            "-g port           wait gdb connection to port\n"
            "-L path           set the elf interpreter prefix (default=%s)\n"
            "-s size           set the stack size in bytes (default=%ld)\n"
-           "-cpu model        select CPU (-cpu ? for list)\n"
+           "-cpu model        select CPU (-cpu help for list)\n"
            "-drop-ld-preload  drop LD_PRELOAD for target process\n"
            "-E var=value      sets/modifies targets environment variable(s)\n"
            "-U var            unsets targets environment variable(s)\n"
@@ -825,7 +825,7 @@ int main(int argc, char **argv)
             qemu_uname_release = argv[optind++];
         } else if (!strcmp(r, "cpu")) {
             cpu_model = argv[optind++];
-            if (strcmp(cpu_model, "?") == 0) {
+            if (is_help_option(cpu_model)) {
 /* XXX: implement xxx_cpu_list for targets that still miss it */
 #if defined(cpu_list)
                     cpu_list(stdout, &fprintf);

diff --git a/hw/mips_jazz.c b/hw/mips_jazz.c
index bf1b799c4d7590d64ef30791eb8395723d367d89..db927f14d02ebcd0766419e642d050308edc2917 100644 (file)
--- a/hw/mips_jazz.c
+++ b/hw/mips_jazz.c
@@ -239,7 +239,7 @@ static void mips_jazz_init(MemoryRegion *address_space,
             dp83932_init(nd, 0x80001000, 2, get_system_memory(), rc4030[4],
                          rc4030_opaque, rc4030_dma_memory_rw);
             break;
-        } else if (strcmp(nd->model, "?") == 0) {
+        } else if (is_help_option(nd->model)) {
             fprintf(stderr, "qemu: Supported NICs: dp83932\n");
             exit(1);
         } else {

diff --git a/hw/qdev-monitor.c b/hw/qdev-monitor.c
index 7915b4500dccfba7b08595f8359349f8f962e09d..b22a37a00c34ad7562173db903707d4bc9c50014 100644 (file)
--- a/hw/qdev-monitor.c
+++ b/hw/qdev-monitor.c
@@ -138,13 +138,13 @@ int qdev_device_help(QemuOpts *opts)
     ObjectClass *klass;
 
     driver = qemu_opt_get(opts, "driver");
-    if (driver && !strcmp(driver, "?")) {
+    if (driver && is_help_option(driver)) {
         bool show_no_user = false;
         object_class_foreach(qdev_print_devinfo, TYPE_DEVICE, false, &show_no_user);
         return 1;
     }
 
-    if (!driver || !qemu_opt_get(opts, "?")) {
+    if (!driver || !qemu_opt_has_help_opt(opts)) {
         return 0;
     }
 

diff --git a/hw/watchdog.c b/hw/watchdog.c
index a42124d5205b163aa100c84288bf484c6e4951be..b52acedd98a1df17ce4f352b72dd85d108f0189c 100644 (file)
--- a/hw/watchdog.c
+++ b/hw/watchdog.c
@@ -55,7 +55,7 @@ int select_watchdog(const char *p)
     QemuOpts *opts;
 
     /* -watchdog ? lists available devices and exits cleanly. */
-    if (strcmp(p, "?") == 0) {
+    if (is_help_option(p)) {
         QLIST_FOREACH(model, &watchdog_list, entry) {
             fprintf(stderr, "\t%s\t%s\n",
                      model->wdt_name, model->wdt_description);

diff --git a/linux-user/main.c b/linux-user/main.c
index a0ab8e839c1147f8d783e56dd715b142c7d839c6..25eaa11a1f17c3f86ef6b2831986554d8730d631 100644 (file)
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -3140,7 +3140,7 @@ static void handle_arg_uname(const char *arg)
 static void handle_arg_cpu(const char *arg)
 {
     cpu_model = strdup(arg);
-    if (cpu_model == NULL || strcmp(cpu_model, "?") == 0) {
+    if (cpu_model == NULL || is_help_option(cpu_model)) {
         /* XXX: implement xxx_cpu_list for targets that still miss it */
 #if defined(cpu_list_id)
         cpu_list_id(stdout, &fprintf, "");
@@ -3231,7 +3231,7 @@ struct qemu_argument arg_table[] = {
     {"s",          "QEMU_STACK_SIZE",  true,  handle_arg_stack_size,
      "size",       "set the stack size to 'size' bytes"},
     {"cpu",        "QEMU_CPU",         true,  handle_arg_cpu,
-     "model",      "select CPU (-cpu ? for list)"},
+     "model",      "select CPU (-cpu help for list)"},
     {"E",          "QEMU_SET_ENV",     true,  handle_arg_set_env,
      "var=value",  "sets targets environment variable (see below)"},
     {"U",          "QEMU_UNSET_ENV",   true,  handle_arg_unset_env,

diff --git a/net.c b/net.c
index dbca77bad16f0e234d189e0e7c95771feb48a58f..32ca50eaf008a34b4b5d77a0b9c81a83d027dbb8 100644 (file)
--- a/net.c
+++ b/net.c
@@ -691,8 +691,9 @@ int qemu_show_nic_models(const char *arg, const char *const *models)
 {
     int i;
 
-    if (!arg || strcmp(arg, "?"))
+    if (!arg || !is_help_option(arg)) {
         return 0;
+    }
 
     fprintf(stderr, "qemu: Supported NIC models: ");
     for (i = 0 ; models[i]; i++)

diff --git a/qemu-common.h b/qemu-common.h
index d26ff39e8768050b3b8aac60849624702dc7dc65..dd919120240d4c3c03d0a0d14d6609cb8e255e40 100644 (file)
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -136,6 +136,24 @@ int qemu_main(int argc, char **argv, char **envp);
 void qemu_get_timedate(struct tm *tm, int offset);
 int qemu_timedate_diff(struct tm *tm);
 
+/**
+ * is_help_option:
+ * @s: string to test
+ *
+ * Check whether @s is one of the standard strings which indicate
+ * that the user is asking for a list of the valid values for a
+ * command option like -cpu or -M. The current accepted strings
+ * are 'help' and '?'. '?' is deprecated (it is a shell wildcard
+ * which makes it annoying to use in a reliable way) but provided
+ * for backwards compatibility.
+ *
+ * Returns: true if @s is a request for a list.
+ */
+static inline bool is_help_option(const char *s)
+{
+    return !strcmp(s, "?") || !strcmp(s, "help");
+}
+
 /* cutils.c */
 void pstrcpy(char *buf, int buf_size, const char *str);
 void strpadcpy(char *buf, int buf_size, const char *str, char pad);

diff --git a/qemu-doc.texi b/qemu-doc.texi
index 84dad1957955578fa797e359926c8f3a9ab1737b..a41448a7a7d962a0de0146aad6abdf0e822b187a 100644 (file)
--- a/qemu-doc.texi
+++ b/qemu-doc.texi
@@ -2390,7 +2390,7 @@ Set the x86 elf interpreter prefix (default=/usr/local/qemu-i386)
 @item -s size
 Set the x86 stack size in bytes (default=524288)
 @item -cpu model
-Select CPU model (-cpu ? for list and additional feature selection)
+Select CPU model (-cpu help for list and additional feature selection)
 @item -ignore-environment
 Start with an empty environment. Without this option,
 the initial environment is a copy of the caller's environment.

diff --git a/qemu-ga.c b/qemu-ga.c
index 8199da789cab6445b4a0e59b1378372638fba680..f1a39ec3a6425d4072d3a871eb3b9643303ea988 100644 (file)
--- a/qemu-ga.c
+++ b/qemu-ga.c
@@ -736,7 +736,7 @@ int main(int argc, char **argv)
             break;
         case 'b': {
             char **list_head, **list;
-            if (*optarg == '?') {
+            if (is_help_option(optarg)) {
                 list_head = list = qmp_get_command_list();
                 while (*list != NULL) {
                     printf("%s\n", *list);

diff --git a/qemu-img.c b/qemu-img.c
index 80cfb9b167a428ea3dab7c9c9c768c2e2f33c867..b866f8081e27cd8cdf69694d1707d5ab4376f77e 100644 (file)
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -350,7 +350,7 @@ static int img_create(int argc, char **argv)
         img_size = (uint64_t)sval;
     }
 
-    if (options && !strcmp(options, "?")) {
+    if (options && is_help_option(options)) {
         ret = print_block_option_help(filename, fmt);
         goto out;
     }
@@ -744,7 +744,7 @@ static int img_convert(int argc, char **argv)
     /* Initialize before goto out */
     qemu_progress_init(progress, 2.0);
 
-    if (options && !strcmp(options, "?")) {
+    if (options && is_help_option(options)) {
         ret = print_block_option_help(out_filename, out_fmt);
         goto out;
     }

diff --git a/qemu-option.c b/qemu-option.c
index 8334190c533fde1b8f6d1c34f937bc10c209200c..27891e74e7c5713aacd902f2dda417097885edfd 100644 (file)
--- a/qemu-option.c
+++ b/qemu-option.c
@@ -529,6 +529,18 @@ const char *qemu_opt_get(QemuOpts *opts, const char *name)
     return opt ? opt->str : NULL;
 }
 
+bool qemu_opt_has_help_opt(QemuOpts *opts)
+{
+    QemuOpt *opt;
+
+    QTAILQ_FOREACH_REVERSE(opt, &opts->head, QemuOptHead, next) {
+        if (is_help_option(opt->name)) {
+            return true;
+        }
+    }
+    return false;
+}
+
 bool qemu_opt_get_bool(QemuOpts *opts, const char *name, bool defval)
 {
     QemuOpt *opt = qemu_opt_find(opts, name);

diff --git a/qemu-option.h b/qemu-option.h
index 951dec3cc40937d0f9e543f02e394dfb9ffcd5d8..ca729862d57bf40804159ee197c7cdab4d80f5f5 100644 (file)
--- a/qemu-option.h
+++ b/qemu-option.h
@@ -107,6 +107,18 @@ struct QemuOptsList {
 };
 
 const char *qemu_opt_get(QemuOpts *opts, const char *name);
+/**
+ * qemu_opt_has_help_opt:
+ * @opts: options to search for a help request
+ *
+ * Check whether the options specified by @opts include one of the
+ * standard strings which indicate that the user is asking for a
+ * list of the valid values for a command line option (as defined
+ * by is_help_option()).
+ *
+ * Returns: true if @opts includes 'help' or equivalent.
+ */
+bool qemu_opt_has_help_opt(QemuOpts *opts);
 bool qemu_opt_get_bool(QemuOpts *opts, const char *name, bool defval);
 uint64_t qemu_opt_get_number(QemuOpts *opts, const char *name, uint64_t defval);
 uint64_t qemu_opt_get_size(QemuOpts *opts, const char *name, uint64_t defval);

diff --git a/qemu-options.hx b/qemu-options.hx
index dc68e150334aa39a8759b6e7da2acf03041299c6..92774147828d61e13673d216a3f6f0c29035313f 100644 (file)
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -6,6 +6,10 @@ HXCOMM construct option structures, enums and help message for specified
 HXCOMM architectures.
 HXCOMM HXCOMM can be used for comments, discarded from both texi and C
 
+HXCOMM TODO : when we are able to change -help output without breaking
+HXCOMM libvirt we should update the help options which refer to -cpu ?,
+HXCOMM -driver ?, etc to use the preferred -cpu help etc instead.
+
 DEFHEADING(Standard options:)
 STEXI
 @table @option

diff --git a/qemu-timer.c b/qemu-timer.c
index de9897788de59a78130874f1cceb26e3d1a0edd2..062fdf2cb9648381b3b63df6bd51cca578a9f751 100644 (file)
--- a/qemu-timer.c
+++ b/qemu-timer.c
@@ -183,7 +183,7 @@ void configure_alarms(char const *opt)
     char *name;
     struct qemu_alarm_timer tmp;
 
-    if (!strcmp(opt, "?")) {
+    if (is_help_option(opt)) {
         show_available_alarms();
         exit(0);
     }

diff --git a/vl.c b/vl.c
index 9fea320bb2a835e4a1d3e427aecaf90e4954dcc5..1fd11148e728db493aaec2f7f53e5d963986dae3 100644 (file)
--- a/vl.c
+++ b/vl.c
@@ -2086,7 +2086,7 @@ static QEMUMachine *machine_parse(const char *name)
         printf("%-20s %s%s\n", m->name, m->desc,
                m->is_default ? " (default)" : "");
     }
-    exit(!name || *name != '?');
+    exit(!name || !is_help_option(name));
 }
 
 static int tcg_init(void)
@@ -3216,7 +3216,7 @@ int main(int argc, char **argv, char **envp)
      */
     cpudef_init();
 
-    if (cpu_model && *cpu_model == '?') {
+    if (cpu_model && is_help_option(cpu_model)) {
         list_cpus(stdout, &fprintf, cpu_model);
         exit(0);
     }