Patchwork [2/8] posix: Use char_array for internal glob dirname

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Submitter Adhemerval Zanella Netto
Date Nov. 21, 2017, 1:55 p.m.
Message ID <1511272530-10936-3-git-send-email-adhemerval.zanella@linaro.org>
Download mbox | patch
Permalink /patch/24404/
State New
Headers show

Comments

Adhemerval Zanella Netto - Nov. 21, 2017, 1:55 p.m.
This is the first patch of the set to remove alloca usage on glob
implementation.  Internal path to search for file might expand to a
non static directory derived from pattern for some difference cases
(GLOB_NOESCAPE, GNU GLOB_TILDE) and to allow a non-static dirname
path glob uses a lot of boilerplate code to manage the buffer (which
is either allocated using alloca or malloc depending both to size
requested and the total alloca_used).

The patch changes to use the char_array struct with the default size
(256 bytes).  It simplifies all the allocation code by using char_array
one and every internal buffer access is done using char_array provided
functions.  No functional changes are expected.

Checked on x86_64-linux-gnu.

	* posix/globc.c (glob): Use char_array for dirname.

Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
---
 ChangeLog    |   2 +
 posix/glob.c | 270 ++++++++++++++++++++++++-----------------------------------
 2 files changed, 112 insertions(+), 160 deletions(-)

Patch

diff --git a/posix/glob.c b/posix/glob.c
index cb39779..7a89d2f 100644
--- a/posix/glob.c
+++ b/posix/glob.c
@@ -77,6 +77,7 @@ 
 #include <flexmember.h>
 #include <glob_internal.h>
 #include <scratch_buffer.h>
+#include <malloc/char_array-skeleton.c>
 
 static const char *next_brace_sub (const char *begin, int flags) __THROWNL;
 
@@ -288,16 +289,15 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 	glob_t *pglob)
 {
   const char *filename;
-  char *dirname = NULL;
   size_t dirlen;
   int status;
   size_t oldcount;
   int meta;
-  int dirname_modified;
-  int malloc_dirname = 0;
+  bool dirname_modified;
   glob_t dirs;
   int retval = 0;
   size_t alloca_used = 0;
+  struct char_array dirname;
 
   if (pattern == NULL || pglob == NULL || (flags & ~__GLOB_FLAGS) != 0)
     {
@@ -305,6 +305,10 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
       return -1;
     }
 
+  /* Default char array is stack allocated, so there is no need to check
+     if setting the initial '\0' succeeds.  */
+  char_array_init_empty (&dirname);
+
   /* POSIX requires all slashes to be matched.  This means that with
      a trailing slash we must match only directories.  */
   if (pattern[0] && pattern[strlen (pattern) - 1] == '/')
@@ -325,12 +329,12 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 	  size_t i;
 
 	  if (pglob->gl_offs >= ~((size_t) 0) / sizeof (char *))
-	    return GLOB_NOSPACE;
+	    goto err_nospace;
 
 	  pglob->gl_pathv = (char **) malloc ((pglob->gl_offs + 1)
 					      * sizeof (char *));
 	  if (pglob->gl_pathv == NULL)
-	    return GLOB_NOSPACE;
+	    goto err_nospace;
 
 	  for (i = 0; i <= pglob->gl_offs; ++i)
 	    pglob->gl_pathv[i] = NULL;
@@ -382,7 +386,7 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 	    {
 	      onealt = malloc (pattern_len);
 	      if (onealt == NULL)
-		return GLOB_NOSPACE;
+		goto err_nospace;
 	    }
 
 	  /* We know the prefix for all sub-patterns.  */
@@ -444,7 +448,8 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 		      globfree (pglob);
 		      pglob->gl_pathc = 0;
 		    }
-		  return result;
+		  retval = result;
+		  goto out;
 		}
 
 	      if (*next == '}')
@@ -461,9 +466,10 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 
 	  if (pglob->gl_pathc != firstc)
 	    /* We found some entries.  */
-	    return 0;
+	    retval = 0;
 	  else if (!(flags & (GLOB_NOCHECK|GLOB_NOMAGIC)))
-	    return GLOB_NOMATCH;
+	    retval = GLOB_NOMATCH;
+	  goto out;
 	}
     }
 
@@ -482,14 +488,15 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
     filename = strchr (pattern, ':');
 #endif /* __MSDOS__ || WINDOWS32 */
 
-  dirname_modified = 0;
+  dirname_modified = false;
   if (filename == NULL)
     {
       /* This can mean two things: a simple name or "~name".  The latter
 	 case is nothing but a notation for a directory.  */
       if ((flags & (GLOB_TILDE|GLOB_TILDE_CHECK)) && pattern[0] == '~')
 	{
-	  dirname = (char *) pattern;
+	  if (!char_array_set_str (&dirname, pattern))
+	    goto err_nospace;
 	  dirlen = strlen (pattern);
 
 	  /* Set FILENAME to NULL as a special flag.  This is ugly but
@@ -506,7 +513,8 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 	    }
 
 	  filename = pattern;
-	  dirname = (char *) ".";
+	  if (!char_array_set_str (&dirname, "."))
+	    goto err_nospace;
 	  dirlen = 0;
 	}
     }
@@ -515,13 +523,13 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 	       && (flags & GLOB_NOESCAPE) == 0))
     {
       /* "/pattern" or "\\/pattern".  */
-      dirname = (char *) "/";
+      if (!char_array_set_str (&dirname, "/"))
+	goto err_nospace;
       dirlen = 1;
       ++filename;
     }
   else
     {
-      char *newp;
       dirlen = filename - pattern;
 #if defined __MSDOS__ || defined WINDOWS32
       if (*filename == ':'
@@ -535,31 +543,25 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 	  /* For now, disallow wildcards in the drive spec, to
 	     prevent infinite recursion in glob.  */
 	  if (__glob_pattern_p (drive_spec, !(flags & GLOB_NOESCAPE)))
-	    return GLOB_NOMATCH;
+	    {
+	      retval = GLOB_NOMATCH;
+	      goto out;
+	    }
 	  /* If this is "d:pattern", we need to copy ':' to DIRNAME
 	     as well.  If it's "d:/pattern", don't remove the slash
 	     from "d:/", since "d:" and "d:/" are not the same.*/
 	}
 #endif
-
-      if (glob_use_alloca (alloca_used, dirlen + 1))
-	newp = alloca_account (dirlen + 1, alloca_used);
-      else
-	{
-	  newp = malloc (dirlen + 1);
-	  if (newp == NULL)
-	    return GLOB_NOSPACE;
-	  malloc_dirname = 1;
-	}
-      *((char *) mempcpy (newp, pattern, dirlen)) = '\0';
-      dirname = newp;
+      if (!char_array_set_str_size (&dirname, pattern, dirlen))
+	goto err_nospace;
       ++filename;
 
 #if defined __MSDOS__ || defined WINDOWS32
       bool drive_root = (dirlen > 1
-                         && (dirname[dirlen - 1] == ':'
-                             || (dirlen > 2 && dirname[dirlen - 2] == ':'
-                                 && dirname[dirlen - 1] == '/')));
+                         && (char_array_pos (&dirname, dirlen - 1) != ':'
+                             || (dirlen > 2
+				 && char_array_pos (&dirname, dirlen - 2) != ':'
+                                 && char_array_pos (&dirname, dirlen - 1) != '/')));
 #else
       bool drive_root = false;
 #endif
@@ -568,20 +570,24 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
         /* "pattern/".  Expand "pattern", appending slashes.  */
 	{
 	  int orig_flags = flags;
-	  if (!(flags & GLOB_NOESCAPE) && dirname[dirlen - 1] == '\\')
+	  if (!(flags & GLOB_NOESCAPE)
+	      && char_array_pos (&dirname, dirlen - 1) == '\\')
 	    {
 	      /* "pattern\\/".  Remove the final backslash if it hasn't
 		 been quoted.  */
-	      char *p = (char *) &dirname[dirlen - 1];
-
-	      while (p > dirname && p[-1] == '\\') --p;
-	      if ((&dirname[dirlen] - p) & 1)
+	      size_t p = dirlen - 1;
+	      while (p > 0 && char_array_pos (&dirname, p - 1) == '\\') --p;
+	      if ((dirlen - p) & 1)
 		{
-		  *(char *) &dirname[--dirlen] = '\0';
+		  /* Since we are shrinking the array, there is no need to
+		     check the function return.  */
+		  dirlen -= 1;
+		  char_array_crop (&dirname, dirlen);
 		  flags &= ~(GLOB_NOCHECK | GLOB_NOMAGIC);
 		}
 	    }
-	  int val = __glob (dirname, flags | GLOB_MARK, errfunc, pglob);
+	  int val = __glob (char_array_str (&dirname), flags | GLOB_MARK,
+			    errfunc, pglob);
 	  if (val == 0)
 	    pglob->gl_flags = ((pglob->gl_flags & ~GLOB_MARK)
 			       | (flags & GLOB_MARK));
@@ -598,11 +604,14 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 	}
     }
 
-  if ((flags & (GLOB_TILDE|GLOB_TILDE_CHECK)) && dirname[0] == '~')
+  if ((flags & (GLOB_TILDE|GLOB_TILDE_CHECK))
+      && char_array_pos (&dirname, 0) == '~')
     {
-      if (dirname[1] == '\0' || dirname[1] == '/'
-	  || (!(flags & GLOB_NOESCAPE) && dirname[1] == '\\'
-	      && (dirname[2] == '\0' || dirname[2] == '/')))
+      if (char_array_pos (&dirname, 1) == '\0'
+	  || char_array_pos (&dirname, 1) == '/'
+	  || (!(flags & GLOB_NOESCAPE) && char_array_pos (&dirname, 1) == '\\'
+	      && (char_array_pos (&dirname, 2) == '\0'
+		  || char_array_pos (&dirname, 2) == '/')))
 	{
 	  /* Look up home directory.  */
 	  char *home_dir = getenv ("HOME");
@@ -652,10 +661,7 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 		  if (err != ERANGE)
 		    break;
 		  if (!scratch_buffer_grow (&s))
-		    {
-		      retval = GLOB_NOSPACE;
-		      goto out;
-		    }
+		    goto err_nospace;
 		}
 	      if (err == 0)
 		{
@@ -664,10 +670,7 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 		}
 	      scratch_buffer_free (&s);
 	      if (err == 0 && home_dir == NULL)
-		{
-		  retval = GLOB_NOSPACE;
-		  goto out;
-		}
+		goto err_nospace;
 #endif /* WINDOWS32 */
 	    }
 	  if (home_dir == NULL || home_dir[0] == '\0')
@@ -686,53 +689,26 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 		}
 	    }
 	  /* Now construct the full directory.  */
-	  if (dirname[1] == '\0')
+	  if (char_array_pos (&dirname, 1) == '\0')
 	    {
-	      if (__glibc_unlikely (malloc_dirname))
-		free (dirname);
-
-	      dirname = home_dir;
-	      dirlen = strlen (dirname);
-	      malloc_dirname = malloc_home_dir;
+	      if (!char_array_set_str (&dirname, home_dir))
+		goto err_nospace;
+	      dirlen = char_array_size (&dirname) - 1;
 	    }
 	  else
 	    {
-	      char *newp;
-	      size_t home_len = strlen (home_dir);
-	      int use_alloca = glob_use_alloca (alloca_used, home_len + dirlen);
-	      if (use_alloca)
-		newp = alloca_account (home_len + dirlen, alloca_used);
-	      else
-		{
-		  newp = malloc (home_len + dirlen);
-		  if (newp == NULL)
-		    {
-		      if (__glibc_unlikely (malloc_home_dir))
-			free (home_dir);
-		      retval = GLOB_NOSPACE;
-		      goto out;
-		    }
-		}
-
-	      mempcpy (mempcpy (newp, home_dir, home_len),
-		       &dirname[1], dirlen);
-
-	      if (__glibc_unlikely (malloc_dirname))
-		free (dirname);
-
-	      dirname = newp;
-	      dirlen += home_len - 1;
-	      malloc_dirname = !use_alloca;
-
-	      if (__glibc_unlikely (malloc_home_dir))
-		free (home_dir);
+	      /* Replaces '~' by the obtained HOME dir.  */
+	      char_array_erase (&dirname, 0);
+	      if (!char_array_prepend_str (&dirname, home_dir))
+		goto err_nospace;
 	    }
-	  dirname_modified = 1;
+	  dirname_modified = true;
 	}
       else
 	{
 #ifndef WINDOWS32
-	  char *end_name = strchr (dirname, '/');
+	  char *dirnamestr = char_array_at (&dirname, 0);
+	  char *end_name = strchr (dirnamestr, '/');
 	  char *user_name;
 	  int malloc_user_name = 0;
 	  char *unescape = NULL;
@@ -741,23 +717,23 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 	    {
 	      if (end_name == NULL)
 		{
-		  unescape = strchr (dirname, '\\');
+		  unescape = strchr (dirnamestr, '\\');
 		  if (unescape)
 		    end_name = strchr (unescape, '\0');
 		}
 	      else
-		unescape = memchr (dirname, '\\', end_name - dirname);
+		unescape = memchr (dirnamestr, '\\', end_name - dirnamestr);
 	    }
 	  if (end_name == NULL)
-	    user_name = dirname + 1;
+	    user_name = dirnamestr + 1;
 	  else
 	    {
 	      char *newp;
-	      if (glob_use_alloca (alloca_used, end_name - dirname))
-		newp = alloca_account (end_name - dirname, alloca_used);
+	      if (glob_use_alloca (alloca_used, end_name - dirnamestr))
+		newp = alloca_account (end_name - dirnamestr, alloca_used);
 	      else
 		{
-		  newp = malloc (end_name - dirname);
+		  newp = malloc (end_name - dirnamestr);
 		  if (newp == NULL)
 		    {
 		      retval = GLOB_NOSPACE;
@@ -767,8 +743,8 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 		}
 	      if (unescape != NULL)
 		{
-		  char *p = mempcpy (newp, dirname + 1,
-				     unescape - dirname - 1);
+		  char *p = mempcpy (newp, dirnamestr + 1,
+				     unescape - dirnamestr - 1);
 		  char *q = unescape;
 		  while (q != end_name)
 		    {
@@ -790,7 +766,8 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 		  *p = '\0';
 		}
 	      else
-		*((char *) mempcpy (newp, dirname + 1, end_name - dirname - 1))
+		*((char *) mempcpy (newp, dirnamestr + 1,
+				    end_name - dirnamestr - 1))
 		  = '\0';
 	      user_name = newp;
 	    }
@@ -824,32 +801,13 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 	    /* If we found a home directory use this.  */
 	    if (p != NULL)
 	      {
-		size_t home_len = strlen (p->pw_dir);
-		size_t rest_len = end_name == NULL ? 0 : strlen (end_name);
-
-		if (__glibc_unlikely (malloc_dirname))
-		  free (dirname);
-		malloc_dirname = 0;
-
-		if (glob_use_alloca (alloca_used, home_len + rest_len + 1))
-		  dirname = alloca_account (home_len + rest_len + 1,
-					    alloca_used);
-		else
+		if (!char_array_set_str (&dirname, p->pw_dir))
 		  {
-		    dirname = malloc (home_len + rest_len + 1);
-		    if (dirname == NULL)
-		      {
-			scratch_buffer_free (&pwtmpbuf);
-			retval = GLOB_NOSPACE;
-			goto out;
-		      }
-		    malloc_dirname = 1;
+		    scratch_buffer_free (&pwtmpbuf);
+		    goto err_nospace;
 		  }
-		*((char *) mempcpy (mempcpy (dirname, p->pw_dir, home_len),
-				    end_name, rest_len)) = '\0';
-
-		dirlen = home_len + rest_len;
-		dirname_modified = 1;
+		dirlen = strlen (p->pw_dir);
+		dirname_modified = true;
 	      }
 	    else
 	      {
@@ -890,37 +848,32 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 	  goto nospace;
 	pglob->gl_pathv = new_gl_pathv;
 
-	if (flags & GLOB_MARK && is_dir (dirname, flags, pglob))
+	if (flags & GLOB_MARK
+	    && is_dir (char_array_str (&dirname), flags, pglob))
 	  {
 	    char *p;
 	    pglob->gl_pathv[newcount] = malloc (dirlen + 2);
 	    if (pglob->gl_pathv[newcount] == NULL)
 	      goto nospace;
-	    p = mempcpy (pglob->gl_pathv[newcount], dirname, dirlen);
+	    p = mempcpy (pglob->gl_pathv[newcount],
+			 char_array_str (&dirname), dirlen);
 	    p[0] = '/';
 	    p[1] = '\0';
-	    if (__glibc_unlikely (malloc_dirname))
-	      free (dirname);
 	  }
 	else
 	  {
-	    if (__glibc_unlikely (malloc_dirname))
-	      pglob->gl_pathv[newcount] = dirname;
-	    else
-	      {
-		pglob->gl_pathv[newcount] = strdup (dirname);
-		if (pglob->gl_pathv[newcount] == NULL)
-		  goto nospace;
-	      }
+	    pglob->gl_pathv[newcount] = strdup (char_array_str (&dirname));
+	    if (pglob->gl_pathv[newcount] == NULL)
+	      goto nospace;
 	  }
 	pglob->gl_pathv[++newcount] = NULL;
 	++pglob->gl_pathc;
 	pglob->gl_flags = flags;
-
-	return 0;
+	goto out;
     }
 
-  meta = __glob_pattern_type (dirname, !(flags & GLOB_NOESCAPE));
+  meta = __glob_pattern_type (char_array_str (&dirname),
+			      !(flags & GLOB_NOESCAPE));
   /* meta is 1 if correct glob pattern containing metacharacters.
      If meta has bit (1 << 2) set, it means there was an unterminated
      [ which we handle the same, using fnmatch.  Broken unterminated
@@ -933,15 +886,15 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 	 the pattern in each directory found.  */
       size_t i;
 
-      if (!(flags & GLOB_NOESCAPE) && dirlen > 0 && dirname[dirlen - 1] == '\\')
+      if (!(flags & GLOB_NOESCAPE) && dirlen > 0
+	  && char_array_pos (&dirname, dirlen - 1) == '\\')
 	{
 	  /* "foo\\/bar".  Remove the final backslash from dirname
 	     if it has not been quoted.  */
-	  char *p = (char *) &dirname[dirlen - 1];
-
-	  while (p > dirname && p[-1] == '\\') --p;
-	  if ((&dirname[dirlen] - p) & 1)
-	    *(char *) &dirname[--dirlen] = '\0';
+	  size_t p = dirlen - 1;
+	  while (p > 0 && char_array_pos (&dirname, p - 1) == '\\') --p;
+	  if ((dirlen - p) & 1)
+	    char_array_crop (&dirname, --dirlen);
 	}
 
       if (__glibc_unlikely ((flags & GLOB_ALTDIRFUNC) != 0))
@@ -955,7 +908,7 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 	  dirs.gl_lstat = pglob->gl_lstat;
 	}
 
-      status = __glob (dirname,
+      status = __glob (char_array_str (&dirname),
 		       ((flags & (GLOB_ERR | GLOB_NOESCAPE | GLOB_ALTDIRFUNC))
 			| GLOB_NOSORT | GLOB_ONLYDIR),
 		       errfunc, &dirs);
@@ -1002,8 +955,7 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 	      globfree (&dirs);
 	      globfree (pglob);
 	      pglob->gl_pathc = 0;
-	      retval = GLOB_NOSPACE;
-	      goto out;
+	      goto err_nospace;
 	    }
 	}
 
@@ -1025,8 +977,7 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 		{
 		nospace2:
 		  globfree (&dirs);
-		  retval = GLOB_NOSPACE;
-		  goto out;
+		  goto err_nospace;
 		}
 
 	      new_gl_pathv = realloc (pglob->gl_pathv,
@@ -1041,8 +992,7 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 		  globfree (&dirs);
 		  globfree (pglob);
 		  pglob->gl_pathc = 0;
-		  retval = GLOB_NOSPACE;
-		  goto out;
+		  goto err_nospace;
 		}
 
 	      ++pglob->gl_pathc;
@@ -1068,7 +1018,7 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 
       if (meta & GLOBPAT_BACKSLASH)
 	{
-	  char *p = strchr (dirname, '\\'), *q;
+	  char *p = strchr (char_array_str (&dirname), '\\'), *q;
 	  /* We need to unescape the dirname string.  It is certainly
 	     allocated by alloca, as otherwise filename would be NULL
 	     or dirname wouldn't contain backslashes.  */
@@ -1085,12 +1035,12 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 	      ++q;
 	    }
 	  while (*p++ != '\0');
-	  dirname_modified = 1;
+	  dirname_modified = true;
 	}
       if (dirname_modified)
 	flags &= ~(GLOB_NOCHECK | GLOB_NOMAGIC);
-      status = glob_in_dir (filename, dirname, flags, errfunc, pglob,
-			    alloca_used);
+      status = glob_in_dir (filename, char_array_str (&dirname), flags,
+			    errfunc, pglob, alloca_used);
       if (status != 0)
 	{
 	  if (status == GLOB_NOMATCH && flags != orig_flags
@@ -1108,14 +1058,13 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
       if (dirlen > 0)
 	{
 	  /* Stick the directory on the front of each name.  */
-	  if (prefix_array (dirname,
+	  if (prefix_array (char_array_str (&dirname),
 			    &pglob->gl_pathv[old_pathc + pglob->gl_offs],
 			    pglob->gl_pathc - old_pathc))
 	    {
 	      globfree (pglob);
 	      pglob->gl_pathc = 0;
-	      retval = GLOB_NOSPACE;
-	      goto out;
+	      goto err_nospace;
 	    }
 	}
     }
@@ -1134,8 +1083,7 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 	      {
 		globfree (pglob);
 		pglob->gl_pathc = 0;
-		retval = GLOB_NOSPACE;
-		goto out;
+		goto err_nospace;
 	      }
 	    strcpy (&new[len - 2], "/");
 	    pglob->gl_pathv[i] = new;
@@ -1151,10 +1099,12 @@  __glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
     }
 
  out:
-  if (__glibc_unlikely (malloc_dirname))
-    free (dirname);
-
+  char_array_free (&dirname);
   return retval;
+
+ err_nospace:
+  char_array_free (&dirname);
+  return GLOB_NOSPACE;
 }
 #if defined _LIBC && !defined __glob
 versioned_symbol (libc, __glob, glob, GLIBC_2_27);