From 9bc7dc01b780a4cfc69c6c3ff6eb9500b2b252da Mon Sep 17 00:00:00 2001
From: Cormac Shannon <>
Date: Sun, 22 Mar 2026 17:04:02 +0000
Subject: [PATCH] Refactor: extract lookup_lush_func, reorder helpers,
 eliminate forward decl

Extract lookup_lush_func() in lcmd.c to deduplicate the registry lookup
pattern shared by try_builtin and exec_user_command. Move exec_user_command
after exec_failed to group helpers together. Move codeenvget definition in
lparser.c to replace its forward declaration.
---
 lcmd.c    | 408 +++++++++++++++++++++++-------------------------------
 lparser.c |  30 ++--
 2 files changed, 189 insertions(+), 249 deletions(-)

diff --git a/lcmd.c b/lcmd.c
index 08cae4c9..f5fd6fdd 100644
--- a/lcmd.c
+++ b/lcmd.c
@@ -607,6 +607,74 @@ static void read_pipes (int fd_out, int fd_err,
 }
 
 
+/* ===== pipeline execution ===== */
+
+/*
+** Build result table {code=N, stdout=S, stderr=S} on the Lua stack.
+*/
+static void push_result_table (lua_State *L, int code,
+                               DynBuf *buf_out, DynBuf *buf_err) {
+  lua_createtable(L, 0, 3);
+  lua_pushinteger(L, code);
+  lua_setfield(L, -2, "code");
+  lua_pushlstring(L, buf_out->data ? buf_out->data : "", buf_out->len);
+  lua_setfield(L, -2, "stdout");
+  lua_pushlstring(L, buf_err->data ? buf_err->data : "", buf_err->len);
+  lua_setfield(L, -2, "stderr");
+}
+
+
+/*
+** Extract exit code from wait status.
+*/
+static int exit_code_from_status (int status) {
+  if (WIFEXITED(status))
+    return WEXITSTATUS(status);
+  else if (WIFSIGNALED(status))
+    return 128 + WTERMSIG(status);
+  return -1;
+}
+
+
+/*
+** Write "name: strerror(errno)\n" to stderr after exec failure.
+** Only called in forked child processes.
+*/
+static void exec_failed (const char *name) {
+  const char *err = strerror(errno);
+  (void)write(STDERR_FILENO, name, strlen(name));
+  (void)write(STDERR_FILENO, ": ", 2);
+  (void)write(STDERR_FILENO, err, strlen(err));
+  (void)write(STDERR_FILENO, "\n", 1);
+}
+
+
+/*
+** Look up a function in lush[table][key].
+** On success, pushes the function and returns 1.
+** On failure, cleans the stack and returns 0.
+*/
+static int lookup_lush_func (lua_State *L, const char *table,
+                             const char *key) {
+  lua_rawgeti(L, LUA_REGISTRYINDEX, LUA_RIDX_LUSH);
+  if (!lua_istable(L, -1)) {
+    lua_pop(L, 1);
+    return 0;
+  }
+  if (lua_getfield(L, -1, table) != LUA_TTABLE) {
+    lua_pop(L, 2);
+    return 0;
+  }
+  if (lua_getfield(L, -1, key) != LUA_TFUNCTION) {
+    lua_pop(L, 3);
+    return 0;
+  }
+  lua_remove(L, -2);  /* remove subtable */
+  lua_remove(L, -2);  /* remove lush table */
+  return 1;
+}
+
+
 /* ===== user command dispatch (runs in forked child) ===== */
 
 /*
@@ -617,21 +685,8 @@ static void read_pipes (int fd_out, int fd_err,
 */
 static int exec_user_command (lua_State *L, ParsedArgs *pa) {
   int i, code = 0;
-  lua_rawgeti(L, LUA_REGISTRYINDEX, LUA_RIDX_LUSH);
-  if (!lua_istable(L, -1)) {
-    lua_pop(L, 1);
+  if (!lookup_lush_func(L, "commands", pa->argv[0]))
     return 0;
-  }
-  if (lua_getfield(L, -1, "commands") != LUA_TTABLE) {
-    lua_pop(L, 2);
-    return 0;
-  }
-  if (lua_getfield(L, -1, pa->argv[0]) != LUA_TFUNCTION) {
-    lua_pop(L, 3);
-    return 0;
-  }
-  lua_remove(L, -2);  /* remove commands table */
-  lua_remove(L, -2);  /* remove lush table */
   for (i = 0; i < pa->argc; i++)
     lua_pushstring(L, pa->argv[i]);
   if (lua_pcall(L, pa->argc, 1, 0) != LUA_OK) {
@@ -658,23 +713,6 @@ static int exec_user_command (lua_State *L, ParsedArgs *pa) {
 }
 
 
-/* ===== pipeline execution ===== */
-
-/*
-** Build result table {code=N, stdout=S, stderr=S} on the Lua stack.
-*/
-static void push_result_table (lua_State *L, int code,
-                               DynBuf *buf_out, DynBuf *buf_err) {
-  lua_createtable(L, 0, 3);
-  lua_pushinteger(L, code);
-  lua_setfield(L, -2, "code");
-  lua_pushlstring(L, buf_out->data ? buf_out->data : "", buf_out->len);
-  lua_setfield(L, -2, "stdout");
-  lua_pushlstring(L, buf_err->data ? buf_err->data : "", buf_err->len);
-  lua_setfield(L, -2, "stderr");
-}
-
-
 /*
 ** Execute a multi-stage pipeline.
 ** stages[0..nstages-1] are command strings. Each is parsed with parse_argv().
@@ -850,17 +888,7 @@ static int exec_pipeline (lua_State *L, char **stages, int nstages,
 
       exec_user_command(L, &pa[i]);
       execvp(pa[i].argv[0], pa[i].argv);
-
-      /* exec failed */
-      {
-        const char *err = strerror(errno);
-        size_t namelen = strlen(pa[i].argv[0]);
-        size_t errlen = strlen(err);
-        (void)write(STDERR_FILENO, pa[i].argv[0], namelen);
-        (void)write(STDERR_FILENO, ": ", 2);
-        (void)write(STDERR_FILENO, err, errlen);
-        (void)write(STDERR_FILENO, "\n", 1);
-      }
+      exec_failed(pa[i].argv[0]);
       _exit(127);
     }
   }
@@ -892,14 +920,8 @@ static int exec_pipeline (lua_State *L, char **stages, int nstages,
   for (i = 0; i < nstages; i++) {
     int status;
     waitpid(pids[i], &status, 0);
-    if (i == nstages - 1) {
-      if (WIFEXITED(status))
-        last_code = WEXITSTATUS(status);
-      else if (WIFSIGNALED(status))
-        last_code = 128 + WTERMSIG(status);
-      else
-        last_code = -1;
-    }
+    if (i == nstages - 1)
+      last_code = exit_code_from_status(status);
   }
   free(pids);
 
@@ -927,21 +949,8 @@ static int exec_pipeline (lua_State *L, char **stages, int nstages,
 */
 static int try_builtin (lua_State *L, ParsedArgs *pa) {
   int i;
-  lua_rawgeti(L, LUA_REGISTRYINDEX, LUA_RIDX_LUSH);
-  if (!lua_istable(L, -1)) {
-    lua_pop(L, 1);
+  if (!lookup_lush_func(L, "builtins", pa->argv[0]))
     return 0;
-  }
-  if (lua_getfield(L, -1, "builtins") != LUA_TTABLE) {
-    lua_pop(L, 2);
-    return 0;
-  }
-  if (lua_getfield(L, -1, pa->argv[0]) != LUA_TFUNCTION) {
-    lua_pop(L, 3);
-    return 0;
-  }
-  lua_remove(L, -2);  /* remove builtins table */
-  lua_remove(L, -2);  /* remove lush table */
   for (i = 0; i < pa->argc; i++)
     lua_pushstring(L, pa->argv[i]);
   lua_call(L, pa->argc, 1);
@@ -1010,6 +1019,97 @@ static int expand_alias (lua_State *L, const char **cmd) {
 }
 
 
+/* ===== single-command fork/exec/wait ===== */
+
+/*
+** Fork, exec a single command, wait, and push a result table.
+** If capture is true, stdout/stderr are captured via pipes.
+** If capture is false, the child inherits the terminal.
+*/
+static void fork_exec_single (lua_State *L, ParsedArgs *pa, int capture) {
+  int out_pipe[2], err_pipe[2];
+  pid_t pid;
+  int status;
+  DynBuf buf_out, buf_err;
+  struct sigaction sa_old_pipe, sa_old_int, sa_old_quit, sa_new;
+
+  if (capture) {
+    if (pipe(out_pipe) != 0)
+      luaL_error(L, "pipe() failed: %s", strerror(errno));
+    if (pipe(err_pipe) != 0) {
+      close(out_pipe[0]); close(out_pipe[1]);
+      luaL_error(L, "pipe() failed: %s", strerror(errno));
+    }
+  }
+
+  memset(&sa_new, 0, sizeof(sa_new));
+  sa_new.sa_handler = SIG_IGN;
+  sigemptyset(&sa_new.sa_mask);
+  sigaction(SIGPIPE, &sa_new, &sa_old_pipe);
+  if (!capture) {
+    sigaction(SIGINT, &sa_new, &sa_old_int);
+    sigaction(SIGQUIT, &sa_new, &sa_old_quit);
+  }
+
+  pid = fork();
+  if (pid < 0) {
+    if (capture) {
+      close(out_pipe[0]); close(out_pipe[1]);
+      close(err_pipe[0]); close(err_pipe[1]);
+    }
+    sigaction(SIGPIPE, &sa_old_pipe, NULL);
+    if (!capture) {
+      sigaction(SIGINT, &sa_old_int, NULL);
+      sigaction(SIGQUIT, &sa_old_quit, NULL);
+    }
+    luaL_error(L, "fork() failed: %s", strerror(errno));
+  }
+
+  if (pid == 0) {
+    /* child */
+    sa_new.sa_handler = SIG_DFL;
+    sigaction(SIGPIPE, &sa_new, NULL);
+    if (!capture) {
+      sigaction(SIGINT, &sa_new, NULL);
+      sigaction(SIGQUIT, &sa_new, NULL);
+    }
+    if (capture) {
+      close(out_pipe[0]);
+      close(err_pipe[0]);
+      dup2(out_pipe[1], STDOUT_FILENO);
+      dup2(err_pipe[1], STDERR_FILENO);
+      close(out_pipe[1]);
+      close(err_pipe[1]);
+    }
+    exec_user_command(L, pa);
+    execvp(pa->argv[0], pa->argv);
+    exec_failed(pa->argv[0]);
+    _exit(127);
+  }
+
+  /* parent */
+  dynbuf_init(&buf_out);
+  dynbuf_init(&buf_err);
+  if (capture) {
+    close(out_pipe[1]);
+    close(err_pipe[1]);
+    read_pipes(out_pipe[0], err_pipe[0], &buf_out, &buf_err);
+  }
+
+  waitpid(pid, &status, 0);
+
+  sigaction(SIGPIPE, &sa_old_pipe, NULL);
+  if (!capture) {
+    sigaction(SIGINT, &sa_old_int, NULL);
+    sigaction(SIGQUIT, &sa_old_quit, NULL);
+  }
+
+  push_result_table(L, exit_code_from_status(status), &buf_out, &buf_err);
+  dynbuf_free(&buf_out);
+  dynbuf_free(&buf_err);
+}
+
+
 /* ===== lushCmd_command ===== */
 
 int lushCmd_command (lua_State *L) {
@@ -1017,11 +1117,7 @@ int lushCmd_command (lua_State *L) {
   char *stages[MAX_PIPELINE_STAGES];
   int nstages;
   ParsedArgs pa;
-  int out_pipe[2], err_pipe[2];
-  pid_t pid;
-  int status;
-  DynBuf buf_out, buf_err;
-  struct sigaction sa_old, sa_new;
+  DynBuf empty_out, empty_err;
 
   /* expand alias before pipeline splitting */
   expand_alias(L, &cmd);
@@ -1047,13 +1143,9 @@ int lushCmd_command (lua_State *L) {
   /* empty command: return {code=0, stdout="", stderr=""} */
   if (pa.argc == 0) {
     free_argv(&pa);
-    lua_createtable(L, 0, 3);
-    lua_pushinteger(L, 0);
-    lua_setfield(L, -2, "code");
-    lua_pushliteral(L, "");
-    lua_setfield(L, -2, "stdout");
-    lua_pushliteral(L, "");
-    lua_setfield(L, -2, "stderr");
+    dynbuf_init(&empty_out);
+    dynbuf_init(&empty_err);
+    push_result_table(L, 0, &empty_out, &empty_err);
     return 1;
   }
 
@@ -1063,96 +1155,8 @@ int lushCmd_command (lua_State *L) {
     return 1;
   }
 
-  /* create pipes */
-  if (pipe(out_pipe) != 0) {
-    free_argv(&pa);
-    return luaL_error(L, "pipe() failed: %s", strerror(errno));
-  }
-  if (pipe(err_pipe) != 0) {
-    close(out_pipe[0]); close(out_pipe[1]);
-    free_argv(&pa);
-    return luaL_error(L, "pipe() failed: %s", strerror(errno));
-  }
-
-  /* ignore SIGPIPE so parent doesn't crash if child exits early */
-  memset(&sa_new, 0, sizeof(sa_new));
-  sa_new.sa_handler = SIG_IGN;
-  sigemptyset(&sa_new.sa_mask);
-  sigaction(SIGPIPE, &sa_new, &sa_old);
-
-  pid = fork();
-  if (pid < 0) {
-    close(out_pipe[0]); close(out_pipe[1]);
-    close(err_pipe[0]); close(err_pipe[1]);
-    free_argv(&pa);
-    sigaction(SIGPIPE, &sa_old, NULL);
-    return luaL_error(L, "fork() failed: %s", strerror(errno));
-  }
-
-  if (pid == 0) {
-    /* child */
-    close(out_pipe[0]);
-    close(err_pipe[0]);
-    dup2(out_pipe[1], STDOUT_FILENO);
-    dup2(err_pipe[1], STDERR_FILENO);
-    close(out_pipe[1]);
-    close(err_pipe[1]);
-
-    /* restore default SIGPIPE for child */
-    sa_new.sa_handler = SIG_DFL;
-    sigaction(SIGPIPE, &sa_new, NULL);
-
-    exec_user_command(L, &pa);
-    execvp(pa.argv[0], pa.argv);
-
-    /* exec failed — write error to stderr and exit */
-    {
-      const char *err = strerror(errno);
-      size_t namelen = strlen(pa.argv[0]);
-      size_t errlen = strlen(err);
-      /* write "cmd: error\n" */
-      (void)write(STDERR_FILENO, pa.argv[0], namelen);
-      (void)write(STDERR_FILENO, ": ", 2);
-      (void)write(STDERR_FILENO, err, errlen);
-      (void)write(STDERR_FILENO, "\n", 1);
-    }
-    _exit(127);
-  }
-
-  /* parent */
-  close(out_pipe[1]);
-  close(err_pipe[1]);
+  fork_exec_single(L, &pa, 1);
   free_argv(&pa);
-
-  dynbuf_init(&buf_out);
-  dynbuf_init(&buf_err);
-  read_pipes(out_pipe[0], err_pipe[0], &buf_out, &buf_err);
-
-  waitpid(pid, &status, 0);
-
-  /* restore old SIGPIPE handler */
-  sigaction(SIGPIPE, &sa_old, NULL);
-
-  /* build result table */
-  lua_createtable(L, 0, 3);
-
-  if (WIFEXITED(status))
-    lua_pushinteger(L, WEXITSTATUS(status));
-  else if (WIFSIGNALED(status))
-    lua_pushinteger(L, 128 + WTERMSIG(status));
-  else
-    lua_pushinteger(L, -1);
-  lua_setfield(L, -2, "code");
-
-  lua_pushlstring(L, buf_out.data ? buf_out.data : "", buf_out.len);
-  lua_setfield(L, -2, "stdout");
-
-  lua_pushlstring(L, buf_err.data ? buf_err.data : "", buf_err.len);
-  lua_setfield(L, -2, "stderr");
-
-  dynbuf_free(&buf_out);
-  dynbuf_free(&buf_err);
-
   return 1;
 }
 
@@ -1188,10 +1192,7 @@ int lushCmd_interactive (lua_State *L) {
   char *stages[MAX_PIPELINE_STAGES];
   int nstages;
   ParsedArgs pa;
-  pid_t pid;
-  int status, code;
-  struct sigaction sa_old_pipe, sa_old_int, sa_old_quit, sa_new;
-  DynBuf buf_out, buf_err;
+  DynBuf empty_out, empty_err;
 
   /* expand alias before pipeline splitting */
   expand_alias(L, &cmd);
@@ -1216,9 +1217,9 @@ int lushCmd_interactive (lua_State *L) {
 
   if (pa.argc == 0) {
     free_argv(&pa);
-    dynbuf_init(&buf_out);
-    dynbuf_init(&buf_err);
-    push_result_table(L, 0, &buf_out, &buf_err);
+    dynbuf_init(&empty_out);
+    dynbuf_init(&empty_err);
+    push_result_table(L, 0, &empty_out, &empty_err);
     lua_setglobal(L, "_");
     return 0;
   }
@@ -1230,69 +1231,10 @@ int lushCmd_interactive (lua_State *L) {
     return 0;
   }
 
-  /* ignore SIGINT, SIGQUIT, SIGPIPE in parent */
-  memset(&sa_new, 0, sizeof(sa_new));
-  sa_new.sa_handler = SIG_IGN;
-  sigemptyset(&sa_new.sa_mask);
-  sigaction(SIGPIPE, &sa_new, &sa_old_pipe);
-  sigaction(SIGINT, &sa_new, &sa_old_int);
-  sigaction(SIGQUIT, &sa_new, &sa_old_quit);
-
-  pid = fork();
-  if (pid < 0) {
-    free_argv(&pa);
-    sigaction(SIGPIPE, &sa_old_pipe, NULL);
-    sigaction(SIGINT, &sa_old_int, NULL);
-    sigaction(SIGQUIT, &sa_old_quit, NULL);
-    return luaL_error(L, "fork() failed: %s", strerror(errno));
-  }
-
-  if (pid == 0) {
-    /* child: restore signal defaults, inherit terminal */
-    sa_new.sa_handler = SIG_DFL;
-    sigaction(SIGPIPE, &sa_new, NULL);
-    sigaction(SIGINT, &sa_new, NULL);
-    sigaction(SIGQUIT, &sa_new, NULL);
-
-    exec_user_command(L, &pa);
-    execvp(pa.argv[0], pa.argv);
-
-    /* exec failed */
-    {
-      const char *err = strerror(errno);
-      size_t namelen = strlen(pa.argv[0]);
-      size_t errlen = strlen(err);
-      (void)write(STDERR_FILENO, pa.argv[0], namelen);
-      (void)write(STDERR_FILENO, ": ", 2);
-      (void)write(STDERR_FILENO, err, errlen);
-      (void)write(STDERR_FILENO, "\n", 1);
-    }
-    _exit(127);
-  }
-
-  /* parent */
+  fork_exec_single(L, &pa, 0);
   free_argv(&pa);
-  waitpid(pid, &status, 0);
-
-  /* restore signals */
-  sigaction(SIGPIPE, &sa_old_pipe, NULL);
-  sigaction(SIGINT, &sa_old_int, NULL);
-  sigaction(SIGQUIT, &sa_old_quit, NULL);
-
-  if (WIFEXITED(status))
-    code = WEXITSTATUS(status);
-  else if (WIFSIGNALED(status))
-    code = 128 + WTERMSIG(status);
-  else
-    code = -1;
-
-  /* build {code=N, stdout="", stderr=""} and set as global _ */
-  dynbuf_init(&buf_out);
-  dynbuf_init(&buf_err);
-  push_result_table(L, code, &buf_out, &buf_err);
   lua_setglobal(L, "_");
-
-  return 0;  /* void — no Lua return values */
+  return 0;
 }
 
 
diff --git a/lparser.c b/lparser.c
index f27c1642..4dc73ee0 100644
--- a/lparser.c
+++ b/lparser.c
@@ -553,7 +553,20 @@ static void singlevar (LexState *ls, expdesc *var) {
 }
 
 
-static void codeenvget (LexState *ls, expdesc *v, TString *name);
+static void codeenvget (LexState *ls, expdesc *v, TString *name) {
+  FuncState *fs = ls->fs;
+  int base, line;
+  expdesc func, arg;
+  line = ls->linenumber;
+  codelushfunc(fs, LUSH_OP_GETENV, &func);
+  base = func.u.info;
+  codestring(&arg, name);
+  luaK_exp2nextreg(fs, &arg);
+  init_exp(v, VCALL, luaK_codeABC(fs, OP_CALL, base, 2, 2));
+  luaK_fixline(fs, line);
+  fs->freereg = cast_byte(base + 1);
+}
+
 
 /*
 ** Parse a single interpolation fragment in a command: ${expr}, $NAME,
@@ -1323,21 +1336,6 @@ static void commandexp (LexState *ls, expdesc *v) {
 }
 
 
-static void codeenvget (LexState *ls, expdesc *v, TString *name) {
-  FuncState *fs = ls->fs;
-  int base, line;
-  expdesc func, arg;
-  line = ls->linenumber;
-  codelushfunc(fs, LUSH_OP_GETENV, &func);
-  base = func.u.info;
-  codestring(&arg, name);
-  luaK_exp2nextreg(fs, &arg);
-  init_exp(v, VCALL, luaK_codeABC(fs, OP_CALL, base, 2, 2));
-  luaK_fixline(fs, line);
-  fs->freereg = cast_byte(base + 1);
-}
-
-
 static void primaryexp (LexState *ls, expdesc *v) {
   /* primaryexp -> NAME | '(' expr ')' | COMMAND | ENVVAR */
   switch (ls->t.token) {