git-sh-i18n--envsubst: our own envsubst(1) for eval_gettext()

Add a git-sh-i18n--envsubst program which is a stripped-down version
of the GNU envsubst(1) program that comes with GNU gettext for use in
the eval_gettext() fallback.

We need a C helper program because implementing eval_gettext() purely
in shell turned out to be unworkable. Digging through the Git mailing
list archives will reveal two shell implementations of eval_gettext
that are almost good enough, but fail on an edge case which is tested
for in the tests which are part of this patch.

These are the modifications I made to envsubst.c as I turned it into
sh-i18n--envsubst.c:

 * Added our git-compat-util.h header for xrealloc() and friends.

 * Removed inclusion of gettext-specific headers.

 * Removed most of main() and replaced it with my own. The modified
   version only does option parsing for --variables. That's all it
   needs.

 * Modified error() invocations to use our error() instead of
   error(3).

 * Replaced the gettext XNMALLOC(n, size) macro with just
   xmalloc(n). Since XNMALLOC() only allocated char's.

 * Removed the string_list_destroy function. It's redundant (also in
   the upstream code).

 * Replaced the use of stdbool.h (a C99 header) by doing the following
   replacements on the code:

    * s/bool/unsigned short int/g
    * s/true/1/g
    * s/false/0/g

Reported-by: Johannes Sixt <j.sixt@viscovery.net>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/.gitignore b/.gitignore
index 711fce7e08beea95d1870047452131e3bf5278dd..1ccf79746ae0cadfe857c7f387e9a28f5d287f0c 100644 (file)
--- a/.gitignore
+++ b/.gitignore
@@ -127,6 +127,8 @@
 /git-rm
 /git-send-email
 /git-send-pack
+/git-sh-i18n
+/git-sh-i18n--envsubst
 /git-sh-setup
 /git-shell
 /git-shortlog

diff --git a/Documentation/git-sh-i18n--envsubst.txt b/Documentation/git-sh-i18n--envsubst.txt
new file mode 100644 (file)
index 0000000..f5bbf77
--- /dev/null
+++ b/Documentation/git-sh-i18n--envsubst.txt
@@ -0,0 +1,26 @@
+git-sh-i18n--envsubst(1)
+========================
+
+NAME
+----
+git-sh-i18n--envsubst - Git's own envsubst(1) for i18n fallbacks
+
+DESCRIPTION
+-----------
+
+This is not a command the end user would want to run.  Ever.
+This documentation is meant for people who are studying the
+plumbing scripts and/or are writing new ones.
+
+git-sh-i18n--envsubst is Git's stripped-down copy of the GNU
+`envsubst(1)` program that comes with the GNU gettext package. It's
+used internally by linkgit:git-sh-i18n[1] to interpolate the variables
+passed to the the `eval_gettext` function.
+
+No promises are made about the interface, or that this
+program won't disappear without warning in the next version
+of Git. Don't use it.
+
+GIT
+---
+Part of the linkgit:git[1] suite

diff --git a/Makefile b/Makefile
index ef57c1c9b40de62d58d192f1f65f65e9e9f19dd8..87c83cb458e6e49c72250db8852c472d3ea73dca 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -414,6 +414,7 @@ PROGRAM_OBJS += shell.o
 PROGRAM_OBJS += show-index.o
 PROGRAM_OBJS += upload-pack.o
 PROGRAM_OBJS += http-backend.o
+PROGRAM_OBJS += sh-i18n--envsubst.o
 
 PROGRAMS += $(patsubst %.o,git-%$X,$(PROGRAM_OBJS))
 

diff --git a/sh-i18n--envsubst.c b/sh-i18n--envsubst.c
new file mode 100644 (file)
index 0000000..7125093
--- /dev/null
+++ b/sh-i18n--envsubst.c
@@ -0,0 +1,444 @@
+/*
+ * sh-i18n--envsubst.c - a stripped-down version of gettext's envsubst(1)
+ *
+ * Copyright (C) 2010 Ævar Arnfjörð Bjarmason
+ *
+ * This is a modified version of
+ * 67d0871a8c:gettext-runtime/src/envsubst.c from the gettext.git
+ * repository. It has been stripped down to only implement the
+ * envsubst(1) features that we need in the git-sh-i18n fallbacks.
+ *
+ * The "Close standard error" part in main() is from
+ * 8dac033df0:gnulib-local/lib/closeout.c. The copyright notices for
+ * both files are reproduced immediately below.
+ */
+
+#include "git-compat-util.h"
+
+/* Substitution of environment variables in shell format strings.
+   Copyright (C) 2003-2007 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2003.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* closeout.c - close standard output and standard error
+   Copyright (C) 1998-2007 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#include <errno.h>
+#include <getopt.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* If true, substitution shall be performed on all variables.  */
+static unsigned short int all_variables;
+
+/* Forward declaration of local functions.  */
+static void print_variables (const char *string);
+static void note_variables (const char *string);
+static void subst_from_stdin (void);
+
+int
+main (int argc, char *argv[])
+{
+  /* Default values for command line options.  */
+  unsigned short int show_variables = 0;
+
+  switch (argc)
+       {
+       case 1:
+         error ("we won't substitute all variables on stdin for you");
+         /*
+         all_variables = 1;
+      subst_from_stdin ();
+         */
+       case 2:
+         /* echo '$foo and $bar' | git sh-i18n--envsubst --variables '$foo and $bar' */
+         all_variables = 0;
+         note_variables (argv[1]);
+      subst_from_stdin ();
+         break;
+       case 3:
+         /* git sh-i18n--envsubst --variables '$foo and $bar' */
+         if (strcmp(argv[1], "--variables"))
+               error ("first argument must be --variables when two are given");
+         show_variables = 1;
+      print_variables (argv[2]);
+         break;
+       default:
+         error ("too many arguments");
+         break;
+       }
+
+  /* Close standard error.  This is simpler than fwriteerror_no_ebadf, because
+     upon failure we don't need an errno - all we can do at this point is to
+     set an exit status.  */
+  errno = 0;
+  if (ferror (stderr) || fflush (stderr))
+    {
+      fclose (stderr);
+      exit (EXIT_FAILURE);
+    }
+  if (fclose (stderr) && errno != EBADF)
+    exit (EXIT_FAILURE);
+
+  exit (EXIT_SUCCESS);
+}
+
+/* Parse the string and invoke the callback each time a $VARIABLE or
+   ${VARIABLE} construct is seen, where VARIABLE is a nonempty sequence
+   of ASCII alphanumeric/underscore characters, starting with an ASCII
+   alphabetic/underscore character.
+   We allow only ASCII characters, to avoid dependencies w.r.t. the current
+   encoding: While "${\xe0}" looks like a variable access in ISO-8859-1
+   encoding, it doesn't look like one in the BIG5, BIG5-HKSCS, GBK, GB18030,
+   SHIFT_JIS, JOHAB encodings, because \xe0\x7d is a single character in these
+   encodings.  */
+static void
+find_variables (const char *string,
+               void (*callback) (const char *var_ptr, size_t var_len))
+{
+  for (; *string != '\0';)
+    if (*string++ == '$')
+      {
+       const char *variable_start;
+       const char *variable_end;
+       unsigned short int valid;
+       char c;
+
+       if (*string == '{')
+         string++;
+
+       variable_start = string;
+       c = *string;
+       if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || c == '_')
+         {
+           do
+             c = *++string;
+           while ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')
+                  || (c >= '0' && c <= '9') || c == '_');
+           variable_end = string;
+
+           if (variable_start[-1] == '{')
+             {
+               if (*string == '}')
+                 {
+                   string++;
+                   valid = 1;
+                 }
+               else
+                 valid = 0;
+             }
+           else
+             valid = 1;
+
+           if (valid)
+             callback (variable_start, variable_end - variable_start);
+         }
+      }
+}
+
+
+/* Print a variable to stdout, followed by a newline.  */
+static void
+print_variable (const char *var_ptr, size_t var_len)
+{
+  fwrite (var_ptr, var_len, 1, stdout);
+  putchar ('\n');
+}
+
+/* Print the variables contained in STRING to stdout, each one followed by a
+   newline.  */
+static void
+print_variables (const char *string)
+{
+  find_variables (string, &print_variable);
+}
+
+
+/* Type describing list of immutable strings,
+   implemented using a dynamic array.  */
+typedef struct string_list_ty string_list_ty;
+struct string_list_ty
+{
+  const char **item;
+  size_t nitems;
+  size_t nitems_max;
+};
+
+/* Initialize an empty list of strings.  */
+static inline void
+string_list_init (string_list_ty *slp)
+{
+  slp->item = NULL;
+  slp->nitems = 0;
+  slp->nitems_max = 0;
+}
+
+/* Append a single string to the end of a list of strings.  */
+static inline void
+string_list_append (string_list_ty *slp, const char *s)
+{
+  /* Grow the list.  */
+  if (slp->nitems >= slp->nitems_max)
+    {
+      size_t nbytes;
+
+      slp->nitems_max = slp->nitems_max * 2 + 4;
+      nbytes = slp->nitems_max * sizeof (slp->item[0]);
+      slp->item = (const char **) xrealloc (slp->item, nbytes);
+    }
+
+  /* Add the string to the end of the list.  */
+  slp->item[slp->nitems++] = s;
+}
+
+/* Compare two strings given by reference.  */
+static int
+cmp_string (const void *pstr1, const void *pstr2)
+{
+  const char *str1 = *(const char **)pstr1;
+  const char *str2 = *(const char **)pstr2;
+
+  return strcmp (str1, str2);
+}
+
+/* Sort a list of strings.  */
+static inline void
+string_list_sort (string_list_ty *slp)
+{
+  if (slp->nitems > 0)
+    qsort (slp->item, slp->nitems, sizeof (slp->item[0]), cmp_string);
+}
+
+/* Test whether a string list contains a given string.  */
+static inline int
+string_list_member (const string_list_ty *slp, const char *s)
+{
+  size_t j;
+
+  for (j = 0; j < slp->nitems; ++j)
+    if (strcmp (slp->item[j], s) == 0)
+      return 1;
+  return 0;
+}
+
+/* Test whether a sorted string list contains a given string.  */
+static int
+sorted_string_list_member (const string_list_ty *slp, const char *s)
+{
+  size_t j1, j2;
+
+  j1 = 0;
+  j2 = slp->nitems;
+  if (j2 > 0)
+    {
+      /* Binary search.  */
+      while (j2 - j1 > 1)
+       {
+         /* Here we know that if s is in the list, it is at an index j
+            with j1 <= j < j2.  */
+         size_t j = (j1 + j2) >> 1;
+         int result = strcmp (slp->item[j], s);
+
+         if (result > 0)
+           j2 = j;
+         else if (result == 0)
+           return 1;
+         else
+           j1 = j + 1;
+       }
+      if (j2 > j1)
+       if (strcmp (slp->item[j1], s) == 0)
+         return 1;
+    }
+  return 0;
+}
+
+
+/* Set of variables on which to perform substitution.
+   Used only if !all_variables.  */
+static string_list_ty variables_set;
+
+/* Adds a variable to variables_set.  */
+static void
+note_variable (const char *var_ptr, size_t var_len)
+{
+  char *string = xmalloc (var_len + 1);
+  memcpy (string, var_ptr, var_len);
+  string[var_len] = '\0';
+
+  string_list_append (&variables_set, string);
+}
+
+/* Stores the variables occurring in the string in variables_set.  */
+static void
+note_variables (const char *string)
+{
+  string_list_init (&variables_set);
+  find_variables (string, &note_variable);
+  string_list_sort (&variables_set);
+}
+
+
+static int
+do_getc (void)
+{
+  int c = getc (stdin);
+
+  if (c == EOF)
+    {
+      if (ferror (stdin))
+       error ("error while reading standard input");
+    }
+
+  return c;
+}
+
+static inline void
+do_ungetc (int c)
+{
+  if (c != EOF)
+    ungetc (c, stdin);
+}
+
+/* Copies stdin to stdout, performing substitutions.  */
+static void
+subst_from_stdin (void)
+{
+  static char *buffer;
+  static size_t bufmax;
+  static size_t buflen;
+  int c;
+
+  for (;;)
+    {
+      c = do_getc ();
+      if (c == EOF)
+       break;
+      /* Look for $VARIABLE or ${VARIABLE}.  */
+      if (c == '$')
+       {
+         unsigned short int opening_brace = 0;
+         unsigned short int closing_brace = 0;
+
+         c = do_getc ();
+         if (c == '{')
+           {
+             opening_brace = 1;
+             c = do_getc ();
+           }
+         if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || c == '_')
+           {
+             unsigned short int valid;
+
+             /* Accumulate the VARIABLE in buffer.  */
+             buflen = 0;
+             do
+               {
+                 if (buflen >= bufmax)
+                   {
+                     bufmax = 2 * bufmax + 10;
+                     buffer = xrealloc (buffer, bufmax);
+                   }
+                 buffer[buflen++] = c;
+
+                 c = do_getc ();
+               }
+             while ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')
+                    || (c >= '0' && c <= '9') || c == '_');
+
+             if (opening_brace)
+               {
+                 if (c == '}')
+                   {
+                     closing_brace = 1;
+                     valid = 1;
+                   }
+                 else
+                   {
+                     valid = 0;
+                     do_ungetc (c);
+                   }
+               }
+             else
+               {
+                 valid = 1;
+                 do_ungetc (c);
+               }
+
+             if (valid)
+               {
+                 /* Terminate the variable in the buffer.  */
+                 if (buflen >= bufmax)
+                   {
+                     bufmax = 2 * bufmax + 10;
+                     buffer = xrealloc (buffer, bufmax);
+                   }
+                 buffer[buflen] = '\0';
+
+                 /* Test whether the variable shall be substituted.  */
+                 if (!all_variables
+                     && !sorted_string_list_member (&variables_set, buffer))
+                   valid = 0;
+               }
+
+             if (valid)
+               {
+                 /* Substitute the variable's value from the environment.  */
+                 const char *env_value = getenv (buffer);
+
+                 if (env_value != NULL)
+                   fputs (env_value, stdout);
+               }
+             else
+               {
+                 /* Perform no substitution at all.  Since the buffered input
+                    contains no other '$' than at the start, we can just
+                    output all the buffered contents.  */
+                 putchar ('$');
+                 if (opening_brace)
+                   putchar ('{');
+                 fwrite (buffer, buflen, 1, stdout);
+                 if (closing_brace)
+                   putchar ('}');
+               }
+           }
+         else
+           {
+             do_ungetc (c);
+             putchar ('$');
+             if (opening_brace)
+               putchar ('{');
+           }
+       }
+      else
+       putchar (c);
+    }
+}

diff --git a/t/t0201-gettext-fallbacks.sh b/t/t0201-gettext-fallbacks.sh
new file mode 100755 (executable)
index 0000000..54d98b9
--- /dev/null
+++ b/t/t0201-gettext-fallbacks.sh
@@ -0,0 +1,51 @@
+#!/bin/sh
+#
+# Copyright (c) 2010 Ævar Arnfjörð Bjarmason
+#
+
+test_description='Gettext Shell fallbacks'
+
+. ./test-lib.sh
+. "$GIT_BUILD_DIR"/git-sh-i18n
+
+test_expect_success 'gettext: our gettext() fallback has pass-through semantics' '
+    printf "test" >expect &&
+    gettext "test" >actual &&
+    test_i18ncmp expect actual &&
+    printf "test more words" >expect &&
+    gettext "test more words" >actual &&
+    test_i18ncmp expect actual
+'
+
+test_expect_success 'eval_gettext: our eval_gettext() fallback has pass-through semantics' '
+    printf "test" >expect &&
+    eval_gettext "test" >actual &&
+    test_i18ncmp expect actual &&
+    printf "test more words" >expect &&
+    eval_gettext "test more words" >actual &&
+    test_i18ncmp expect actual
+'
+
+test_expect_success 'eval_gettext: our eval_gettext() fallback can interpolate variables' '
+    printf "test YesPlease" >expect &&
+    GIT_INTERNAL_GETTEXT_TEST_FALLBACKS=YesPlease eval_gettext "test \$GIT_INTERNAL_GETTEXT_TEST_FALLBACKS" >actual &&
+    test_i18ncmp expect actual
+'
+
+test_expect_success 'eval_gettext: our eval_gettext() fallback can interpolate variables with spaces' '
+    cmdline="git am" &&
+    export cmdline;
+    printf "When you have resolved this problem run git am --resolved." >expect &&
+    eval_gettext "When you have resolved this problem run \$cmdline --resolved." >actual
+    test_i18ncmp expect actual
+'
+
+test_expect_success 'eval_gettext: our eval_gettext() fallback can interpolate variables with spaces and quotes' '
+    cmdline="git am" &&
+    export cmdline;
+    printf "When you have resolved this problem run \"git am --resolved\"." >expect &&
+    eval_gettext "When you have resolved this problem run \"\$cmdline --resolved\"." >actual
+    test_i18ncmp expect actual
+'
+
+test_done