lib/tpm2_options.c

@@ -37,6 +37,9 @@
 #include <getopt.h>
 #include <unistd.h>
 
+#include <sys/types.h>
+#include <sys/wait.h>
+
 #include "log.h"
 #include "tpm2_options.h"
 #include "tpm2_util.h"
@@ -199,17 +202,31 @@ static char *tcti_get_opts(char *optstr) {
     return &split[1];
 }
 
-static void execute_man (char *prog_name, char *envp[]) {
+static bool execute_man(char *prog_name) {
 
-    char *manpage = basename(prog_name);
-    char *argv[] = {
-        "/man", // ARGv[0] needs to be something.
-        manpage,
-        NULL
-    };
-    execvpe ("man", argv, envp);
-    LOG_ERR("Could not execute \"man %s\" error: %s", manpage,
-            strerror(errno));
+    pid_t  pid;
+    int status;
+
+    if ((pid = fork()) < 0) {
+        LOG_ERR("Could not fork process to execute man, error: %s",
+                strerror(errno));
+        return false;
+    }
+
+    if (pid == 0) {
+        char *manpage = basename(prog_name);
+        execlp("man", "man", manpage, NULL);
+    } else {
+        if ((pid = waitpid(pid, &status, 0)) == -1) {
+            LOG_ERR("Waiting for child process that executes man failed, error: %s",
+                    strerror(errno));
+            return false;
+        }
+
+        return WEXITSTATUS(status) == 0;
+    }
+
+    return true;
 }
 
 static void show_version (const char *name) {
@@ -236,6 +253,30 @@ static void show_version (const char *name) {
             tcti_conf);
 }
 
+void tpm2_print_usage(const char *command, struct tpm2_options *tool_opts) {
+    unsigned int i;
+
+    printf("usage: %s%s%s\n", command,
+           tool_opts->callbacks.on_opt ? " [OPTIONS]" : "",
+           tool_opts->callbacks.on_arg ? " ARGUMENTS" : "");
+
+    if (tool_opts->callbacks.on_opt) {
+        for (i = 0; i < tool_opts->len; i++) {
+            struct option *opt = &tool_opts->long_opts[i];
+            printf("[ -%c | --%s%s]", opt->val, opt->name,
+                   opt->has_arg ? "=VALUE" : "");
+            if ((i + 1) % 4 == 0) {
+                printf("\n");
+            } else {
+                printf(" ");
+            }
+        }
+        if (i % 4 != 0) {
+            printf("\n");
+        }
+    }
+}
+
 tpm2_option_code tpm2_handle_options (int argc, char **argv, char **envp,
         tpm2_options *tool_opts, tpm2_option_flags *flags,
         TSS2_TCTI_CONTEXT **tcti) {
@@ -291,7 +332,9 @@ tpm2_option_code tpm2_handle_options (int argc, char **argv, char **envp,
             tcti_opts = tcti_get_opts(optarg);
             break;
         case 'h':
-            execute_man(argv[0], envp);
+            if (!execute_man(argv[0])) {
+                tpm2_print_usage(argv[0], tool_opts);
+            }
             show_help = false;
             goto out;
             break;

lib/tpm2_options.h

@@ -186,4 +186,14 @@ tpm2_option_code tpm2_handle_options (int argc, char **argv, char **envp,
         tpm2_options *tool_opts, tpm2_option_flags *flags,
         TSS2_TCTI_CONTEXT **tcti);
 
+/**
+ * Print usage summary for a given tpm2 tool.
+ *
+ * @param command
+ *  The command to print its usage summary text.
+ * @param tool_opts
+ *  The tpm2_options array that contains the tool options to print as a summary.
+ */
+void tpm2_print_usage(const char *command, struct tpm2_options *tool_opts);
+
 #endif /* OPTIONS_H */

tools/tpm2_tool.c

@@ -93,30 +93,6 @@ static TSS2_SYS_CONTEXT* sapi_ctx_init(TSS2_TCTI_CONTEXT *tcti_ctx) {
     return sapi_ctx;
 }
 
-void print_usage(const char *command, struct tpm2_options *tool_opts) {
-    unsigned int i;
-
-    tpm2_tool_output("usage: %s%s%s\n", command,
-                     tool_opts->callbacks.on_opt ? " [OPTIONS]" : "",
-                     tool_opts->callbacks.on_arg ? " ARGUMENTS" : "");
-
-    if (tool_opts->callbacks.on_opt) {
-        for (i = 0; i < tool_opts->len; i++) {
-            struct option *opt = &tool_opts->long_opts[i];
-            tpm2_tool_output("[ -%c | --%s%s]", opt->val, opt->name,
-                             opt->has_arg ? "=VALUE" : "");
-            if ((i + 1) % 4 == 0) {
-                tpm2_tool_output("\n");
-            } else {
-                tpm2_tool_output(" ");
-            }
-        }
-        if (i % 4 != 0) {
-            tpm2_tool_output("\n");
-        }
-    }
-}
-
 /*
  * This program is a template for TPM2 tools that use the SAPI. It does
  * nothing more than parsing command line options that allow the caller to
@@ -136,7 +112,7 @@ int main(int argc, char *argv[], char *envp[]) {
     }
 
     if (argc == 1 && tool_opts && tool_opts->show_usage) {
-        print_usage(argv[0], tool_opts);
+        tpm2_print_usage(argv[0], tool_opts);
         return ret;
     }