[WIP RFC/PATCH] WIP: git-sh-i18n--envsubst for a correct eval_gettext

[WIP RFC/PATCH] WIP: git-sh-i18n--envsubst for a correct eval_gettext

[Ævar Arnfjörð Bjarmason]

t/t0201-gettext-fallbacks.sh: test for broken eval_gettext

Add a test for the broken eval_gettext() variable interpolation
behavior.

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

git-sh-i18n.sh: use envsubst

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>

WIP: add a git-sh-i18n--envsubst

I can't figure out how to make the Makefile read from
git-sh-i18n--envsubst.c and produce git-sh-i18n--envsubst, not
git-git-sh-i18n--envsubst.

I also can't see how to make it available to git tests.

If I name it sh-i18n--envsubst.c I'll get linking errors (about
xrealloc).
---

Heading out so I thought I'd dump a WIP patch here and ask if anyone
knows how to solve this Makefile issue I'm having.

I wanted to call the two programs
/{git-sh-i18n.sh,git-sh-i18n--envsubst.c}, but maybe going that route
is the wrong thing to do?

 .gitignore                   |    1 +
 Makefile                     |    3 +
 git-sh-i18n--envsubst.c      |  392 ++++++++++++++++++++++++++++++++++++++++++
 git-sh-i18n.sh               |    3 +-
 t/t0201-gettext-fallbacks.sh |   23 +++
 5 files changed, 420 insertions(+), 2 deletions(-)
 create mode 100644 git-sh-i18n--envsubst.c

diff --git a/.gitignore b/.gitignore
index 80ca718..d2d9ec2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -126,6 +126,7 @@
 /git-send-email
 /git-send-pack
 /git-sh-i18n
+/git-sh-i18n--envsubst
 /git-sh-setup
 /git-shell
 /git-shortlog
diff --git a/Makefile b/Makefile
index e1650ba..cdfe6bc 100644
--- a/Makefile
+++ b/Makefile
@@ -435,6 +435,7 @@ PROGRAM_OBJS += shell.o
 PROGRAM_OBJS += show-index.o
 PROGRAM_OBJS += upload-pack.o
 PROGRAM_OBJS += http-backend.o
+PROGRAM_OBJS += git-sh-i18n--envsubst.o
 
 PROGRAMS += $(patsubst %.o,git-%$X,$(PROGRAM_OBJS))
 
@@ -2016,6 +2017,8 @@ git-http-fetch$X: revision.o http.o http-walker.o http-fetch.o $(GITLIBS)
 git-http-push$X: revision.o http.o http-push.o $(GITLIBS)
 	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) \
 		$(LIBS) $(CURL_LIBCURL) $(EXPAT_LIBEXPAT)
+git-sh-i18n--envsubst$X: git-sh-i18n--envsubst.o $(GITLIBS)
+	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^)
 
 $(REMOTE_CURL_ALIASES): $(REMOTE_CURL_PRIMARY)
 	$(QUIET_LNCP)$(RM) $@ && \
diff --git a/git-sh-i18n--envsubst.c b/git-sh-i18n--envsubst.c
new file mode 100644
index 0000000..3be7e8e
--- /dev/null
+++ b/git-sh-i18n--envsubst.c
@@ -0,0 +1,392 @@
+/* This is a modified version of
+   67d0871a8c:gettext-runtime/src/envsubst.c from the gettext.git
+   repository that does only the envsubst that we need in the
+   git-sh-i18n fallbacks.
+*/
+
+#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.  */
+
+#include <errno.h>
+#include <getopt.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* If true, substitution shall be performed on all variables.  */
+static bool all_variables;
+
+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[])
+{
+  all_variables = true;
+  subst_from_stdin ();
+
+  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;
+	bool 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 = true;
+		  }
+		else
+		  valid = false;
+	      }
+	    else
+	      valid = true;
+
+	    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;
+}
+
+/* Destroy a list of strings.  */
+static inline void
+string_list_destroy (string_list_ty *slp)
+{
+  size_t j;
+
+  for (j = 0; j < slp->nitems; ++j)
+    free ((char *) slp->item[j]);
+  if (slp->item != NULL)
+    free (slp->item);
+}
+
+
+/* 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 ()
+{
+  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 ()
+{
+  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 ${VARIABLE}.  */
+      if (c == '$')
+	{
+	  bool opening_brace = false;
+	  bool closing_brace = false;
+
+	  c = do_getc ();
+	  if (c == '{')
+	    {
+	      opening_brace = true;
+	      c = do_getc ();
+	    }
+	  if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || c == '_')
+	    {
+	      bool 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 = true;
+		      valid = true;
+		    }
+		  else
+		    {
+		      valid = false;
+		      do_ungetc (c);
+		    }
+		}
+	      else
+		{
+		  valid = true;
+		  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 = false;
+		}
+
+	      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/git-sh-i18n.sh b/git-sh-i18n.sh
index f8dd43a..b3b599a 100644
--- a/git-sh-i18n.sh
+++ b/git-sh-i18n.sh
@@ -55,8 +55,7 @@ then
 		}
 
 		eval_gettext () {
-			gettext_eval="printf '%s' \"$1\""
-			printf "%s" "`eval \"$gettext_eval\"`"
+			printf "%s" "$1" | /home/avar/g/git/git-git-sh-i18n--envsubst
 		}
 	fi
 else
diff --git a/t/t0201-gettext-fallbacks.sh b/t/t0201-gettext-fallbacks.sh
index 7a85d9b..682c602 100755
--- a/t/t0201-gettext-fallbacks.sh
+++ b/t/t0201-gettext-fallbacks.sh
@@ -46,4 +46,27 @@ test_expect_success NO_GETTEXT_POISON 'eval_gettext: our eval_gettext() fallback
     test_cmp expect actual
 '
 
+test_expect_success NO_GETTEXT_POISON 'eval_gettext: our eval_gettext() fallback can interpolate whitespace variables' '
+    git_am_cmdline="git am" &&
+    export git_am_cmdline &&
+    printf "test git am" >expect &&
+    eval_gettext "test \$git_am_cmdline" >actual &&
+    test_cmp expect actual
+'
+
+test_expect_success NO_GETTEXT_POISON 'eval_gettext: git am $cmdline bug' '
+    cmdline="git am -3" &&
+    export cmdline &&
+    cat >expect <<EOF &&
+When you have resolved this problem run "git am -3 --resolved".
+If you would prefer to skip this patch, instead run "git am -3 --skip".
+To restore the original branch and stop patching run "git am -3 --abort".
+EOF
+    eval_gettext "When you have resolved this problem run \"\$cmdline --resolved\".
+If you would prefer to skip this patch, instead run \"\$cmdline --skip\".
+To restore the original branch and stop patching run \"\$cmdline --abort\"." >actual &&
+    echo >>actual &&
+    test_cmp expect actual
+'
+
 test_done
-- 
1.7.3.2.309.g4cea8.dirty