win32: rework adding of extensions to filenames

Previously there was one function to handle adding extensions to
executable filenames, add_win32_extension().  Refactor this into
three functions:

add_win32_extension() appends the suffix to the argument string
in-place.  The argument must be long enough to cope with this,
as is the case in ash where path_advance() adds 4 bytes to each
filename for just this reason.

alloc_win32_extension() is equivalent to the old add_win32_extension().
It allocates a string to hold the new filename then calls the new
add_win32_extension() function.  The caller is responsible for
managing the returned string.

auto_win32_extension() calls alloc_win32_extension() and saves the
resulting string using auto_string().  It's used where the new
filename is consumed immediately or the actual value isn't needed.

Rewrite code to use the most appropriate function.  Also reorder
some code in find_executable() and find_command().

1 files changed, 8 insertions, 52 deletions

diff --git a/shell/ash.c b/shell/ash.c
index cbe30a78b..587cf2abb 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -8405,7 +8405,7 @@ tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) const char *cmd, char **argv, c
 
 #if ENABLE_PLATFORM_MINGW32
         {
-                char *new_cmd = add_win32_extension(cmd);
+                char *new_cmd = alloc_win32_extension(cmd);
                 execve(new_cmd ? new_cmd : cmd, argv, envp);
                 free(new_cmd);
         }
@@ -8516,9 +8516,6 @@ printentry(struct tblentry *cmdp)
         int idx;
         const char *path;
         char *name;
-#if ENABLE_PLATFORM_MINGW32
-        char *n;
-#endif
 
         idx = cmdp->param.index;
         path = pathval();
@@ -8527,13 +8524,9 @@ printentry(struct tblentry *cmdp)
                 stunalloc(name);
         } while (--idx >= 0);
 #if ENABLE_PLATFORM_MINGW32
-        if ((n=add_win32_extension(name)) != NULL)
-                name = n;
+        add_win32_extension(name);
 #endif
         out1fmt("%s%s\n", name, (cmdp->rehash ? "*" : nullstr));
-#if ENABLE_PLATFORM_MINGW32
-        free(n);
-#endif
 }
 
 /*
@@ -8921,9 +8914,6 @@ describe_command(char *command, const char *path, int describe_command_verbose)
         case CMDNORMAL: {
                 int j = entry.u.index;
                 char *p;
-#if ENABLE_PLATFORM_MINGW32
-                char *q;
-#endif
                 if (j < 0) {
                         p = command;
                 } else {
@@ -8933,17 +8923,13 @@ describe_command(char *command, const char *path, int describe_command_verbose)
                         } while (--j >= 0);
                 }
 #if ENABLE_PLATFORM_MINGW32
-                if ((q=add_win32_extension(p)) != NULL)
-                        p = q;
+                add_win32_extension(p);
 #endif
                 if (describe_command_verbose) {
                         out1fmt(" is %s", p);
                 } else {
                         out1str(p);
                 }
-#if ENABLE_PLATFORM_MINGW32
-                free(q);
-#endif
                 break;
         }
 
@@ -13826,36 +13812,28 @@ find_command(char *name, struct cmdentry *entry, int act, const char *path)
         struct tblentry *cmdp;
         int idx;
         int prev;
-        char *fullname IF_PLATFORM_MINGW32(= NULL);
+        char *fullname;
         struct stat statb;
         int e;
         int updatetbl;
         struct builtincmd *bcmd;
-#if ENABLE_PLATFORM_MINGW32
-        extern const char win_suffix[4][4];
-        int i, len;
-#endif
 
         /* If name contains a slash, don't use PATH or hash table */
         if (strchr(name, '/') || (ENABLE_PLATFORM_MINGW32 && strchr(name, '\\'))) {
                 entry->u.index = -1;
                 if (act & DO_ABS) {
 #if ENABLE_PLATFORM_MINGW32
-                        while ((fullname=add_win32_extension(name)) == NULL &&
-                                        stat(name, &statb) < 0 ) {
+                        if (auto_win32_extension(name) == NULL && stat(name, &statb) < 0) {
 #else
                         while (stat(name, &statb) < 0) {
-#endif
 #ifdef SYSV
                                 if (errno == EINTR)
                                         continue;
 #endif
+#endif
                                 entry->cmdtype = CMDUNKNOWN;
                                 return;
                         }
-#if ENABLE_PLATFORM_MINGW32
-                        free(fullname);
-#endif
                 }
                 entry->cmdtype = CMDNORMAL;
                 return;
@@ -13959,29 +13937,8 @@ find_command(char *name, struct cmdentry *entry, int act, const char *path)
                         goto success;
                 }
 #if ENABLE_PLATFORM_MINGW32
-                /* first try appending suffixes (unless there's one already) */
-                i = 4;
-                len = strlen(fullname);
-                if (!has_exe_suffix_or_dot(fullname)) {
-                        /* path_advance() has reserved space for suffix */
-                        fullname[len] = '.';
-                        for (i=0; i<4; ++i) {
-                                memcpy(fullname+len+1, win_suffix[i], 4);
-                                if (stat(fullname, &statb) == 0)
-                                        break;
-                        }
-                }
-
-                if (i == 4) {
-                        /* adding a suffix failed (or wasn't tried), try original */
-                        fullname[len] = '\0';
-                        if (stat(fullname, &statb) < 0) {
-                                if (errno != ENOENT && errno != ENOTDIR)
-                                        e = errno;
-                                goto loop;
-                        }
-                }
-#else
+                add_win32_extension(fullname);
+#endif
                 while (stat(fullname, &statb) < 0) {
 #ifdef SYSV
                         if (errno == EINTR)
@@ -13991,7 +13948,6 @@ find_command(char *name, struct cmdentry *entry, int act, const char *path)
                                 e = errno;
                         goto loop;
                 }
-#endif
                 e = EACCES;     /* if we fail, this will be the error */
                 if (!S_ISREG(statb.st_mode))
                         continue;