fix: pcc-asm 支持 -o 输出文件和符号过滤

- 新增 -o <file> 输出汇编到文件
- 支持过滤+输出组合 (pcc-asm app.exe callq -o calls.txt)
- 修复 cmd /c 引号处理（CreateProcess 不解析 > 重定向）
- 修复参数解析（-o 不再被当作过滤词）

tools/pcc-asm.c

@@ -5,8 +5,10 @@
  *  Uses llvm-objdump if available, else objdump.
  *
  *  Usage:
- *    pcc-asm program.exe          disassemble all code
- *    pcc-asm program.exe main     disassemble, filter by symbol
+ *    pcc-asm program.exe                 disassemble all code (stdout)
+ *    pcc-asm program.exe -o out.asm      disassemble, save to file
+ *    pcc-asm program.exe main            disassemble, filter by symbol
+ *    pcc-asm program.exe main -o out.asm filter and save
  *
  *  License: MIT
  */
@@ -17,6 +19,9 @@
 
 #ifdef _WIN32
 # include <windows.h>
+#else
+# include <unistd.h>
+# include <sys/wait.h>
 #endif
 
 static int file_exists(const char *f)
@@ -28,7 +33,6 @@ static int file_exists(const char *f)
 
 static const char *find_objdump(void)
 {
-    /* common locations, first match wins */
     static const char *cands[] = {
         "llvm-objdump.exe",
         "objdump.exe",
@@ -43,67 +47,105 @@ static const char *find_objdump(void)
     for (i = 0; cands[i]; i++)
         if (file_exists(cands[i]))
             return cands[i];
-    return "objdump";  /* hope it's in PATH */
+    return "objdump";
+}
+
+/* run a command line; Windows uses cmd /c so that shell
+   redirection (>) and pipes (|) work */
+static void run_cmd(const char *cmd)
+{
+#ifdef _WIN32
+    STARTUPINFOA si;
+    PROCESS_INFORMATION pi;
+    char *full = (char*)malloc(strlen(cmd) + 24);
+    if (!full) return;
+    /* cmd /c "cmd"  - double quotes so embedded quotes survive */
+    strcpy(full, "cmd /c \"");
+    strcat(full, cmd);
+    strcat(full, "\"");
+    memset(&si, 0, sizeof si);
+    si.cb = sizeof si;
+    if (CreateProcessA(NULL, full, NULL, NULL, FALSE, 0, NULL, NULL, &si, &pi)) {
+        WaitForSingleObject(pi.hProcess, INFINITE);
+        CloseHandle(pi.hProcess);
+        CloseHandle(pi.hThread);
+    }
+    free(full);
+#else
+    system(cmd);
+#endif
 }
 
 int main(int argc, char **argv)
 {
     const char *objdump = find_objdump();
-    const char *file;
+    const char *file = NULL;
     const char *filter = NULL;
-    char cmd[1024];
+    const char *outfile = NULL;
+    char cmd[2048];
     int len;
+    int i;
+    const char *tmpfile = NULL;
 
-    if (argc < 2) {
+    /* parse args: file [filter] [-o outfile] */
+    for (i = 1; i < argc; i++) {
+        if (strcmp(argv[i], "-o") == 0 && i + 1 < argc) {
+            outfile = argv[++i];
+        } else if (!file) {
+            file = argv[i];
+        } else if (!filter) {
+            filter = argv[i];
+        } else {
+            fprintf(stderr, "pcc-asm: too many arguments\n");
+            return 1;
+        }
+    }
+
+    if (!file) {
         fprintf(stderr,
             "pcc-asm - disassemble a PCC binary\n"
             "\n"
             "Usage:\n"
-            "  pcc-asm program.exe          disassemble all code\n"
-            "  pcc-asm program.exe main     disassemble, filter by symbol\n"
+            "  pcc-asm program.exe                 disassemble all code\n"
+            "  pcc-asm program.exe -o out.asm      save to file\n"
+            "  pcc-asm program.exe main            filter by symbol\n"
+            "  pcc-asm program.exe main -o out.asm filter and save\n"
             "\n"
             "Uses %s\n", objdump);
         return 1;
     }
 
-    file = argv[1];
-    if (argc > 2)
-        filter = argv[2];
-
     if (!file_exists(file)) {
         fprintf(stderr, "pcc-asm: cannot open '%s'\n", file);
         return 1;
     }
 
-#ifdef _WIN32
-    len = snprintf(cmd, sizeof cmd, "\"%s\" -d \"%s\"", objdump, file);
-#else
-    len = snprintf(cmd, sizeof cmd, "%s -d \"%s\"", objdump, file);
-#endif
-
-    if (filter) {
-        /* use objdump's symbol filter if supported, else grep-style */
-        len += snprintf(cmd + len, sizeof cmd - len, " | findstr /c:\"%s\"", filter);
+    /* Step 1: disassemble.
+       If filtering, first write full output to a temp file,
+       then filter that file. */
+    if (filter && outfile) {
+        /* need a temp file for the full listing */
+        static char tmp[L_tmpnam + 1];
+        tmpfile = tmpnam(tmp);
+        if (!tmpfile) { fprintf(stderr, "pcc-asm: tmpnam failed\n"); return 1; }
+        len = snprintf(cmd, sizeof cmd, "\"%s\" -d \"%s\" > \"%s\"", objdump, file, tmpfile);
+        run_cmd(cmd);
+        /* then filter temp -> outfile */
+        len = snprintf(cmd, sizeof cmd, "findstr /c:\"%s\" \"%s\" > \"%s\"", filter, tmpfile, outfile);
+        run_cmd(cmd);
+        remove(tmpfile);
+        printf("pcc-asm: wrote %s\n", outfile);
+    } else if (filter) {
+        len = snprintf(cmd, sizeof cmd, "\"%s\" -d \"%s\" | findstr /c:\"%s\"", objdump, file, filter);
+        run_cmd(cmd);
+    } else if (outfile) {
+        len = snprintf(cmd, sizeof cmd, "\"%s\" -d \"%s\" > \"%s\"", objdump, file, outfile);
+        run_cmd(cmd);
+        printf("pcc-asm: wrote %s\n", outfile);
+    } else {
+        len = snprintf(cmd, sizeof cmd, "\"%s\" -d \"%s\"", objdump, file);
+        run_cmd(cmd);
     }
-
-#ifdef _WIN32
-    {
-        STARTUPINFOA si;
-        PROCESS_INFORMATION pi;
-        char *cmdline = (char*)malloc(strlen(cmd) + 1);
-        if (!cmdline) return 1;
-        strcpy(cmdline, cmd);
-        memset(&si, 0, sizeof si);
-        si.cb = sizeof si;
-        if (CreateProcessA(NULL, cmdline, NULL, NULL, FALSE, 0, NULL, NULL, &si, &pi)) {
-            WaitForSingleObject(pi.hProcess, INFINITE);
-            CloseHandle(pi.hProcess);
-            CloseHandle(pi.hThread);
-        }
-        free(cmdline);
-    }
-#else
-    system(cmd);
-#endif
+    (void)len;
     return 0;
 }