gdb: Move construct_inferior_arguments to gdbsupport

This moves the function construct_inferior_arguments from
gdb/inferior.h and gdb/infcmd.c to gdbsupport/common-inferior.{h,cc}.
While at it, also move the function's comment to the header file
to align with current standards.

The intention is to use it from gdbserver in a follow-up commit.

gdb/ChangeLog:

	* infcmd.c, inferior.h: (construct_inferior_arguments):
	Moved function from here to gdbsupport/common-inferior.{h,cc}

gdbsupport/ChangeLog:

	* common-inferior.h, common-inferior.cc: (construct_inferior_arguments):
	Move function here from gdb/infcmd.c, gdb/inferior.h

Change-Id: Ib9290464ce8c0872f605d8829f88352d064c30d6

3 files changed, 131 insertions, 0 deletions

diff --git a/gdbsupport/ChangeLog b/gdbsupport/ChangeLog
index e7374ab..4f72c7d 100644
--- a/gdbsupport/ChangeLog
+++ b/gdbsupport/ChangeLog
@@ -1,3 +1,8 @@
+2020-05-25  Michael Weghorn  <m.weghorn@posteo.de>
+
+	* common-inferior.h, common-inferior.cc: (construct_inferior_arguments):
+	Move function here from gdb/infcmd.c, gdb/inferior.h
+
 2020-05-14  Kevin Buettner  <kevinb@redhat.com>
 
 	* btrace-common.h (btrace_cpu_vendor): Add CV_AMD.
diff --git a/gdbsupport/common-inferior.cc b/gdbsupport/common-inferior.cc
index ed16e89..a7d631f 100644
--- a/gdbsupport/common-inferior.cc
+++ b/gdbsupport/common-inferior.cc
@@ -24,3 +24,125 @@
 /* See common-inferior.h.  */
 
 bool startup_with_shell = true;
+
+/* See common-inferior.h.  */
+
+char *
+construct_inferior_arguments (int argc, char **argv)
+{
+  char *result;
+
+  /* ARGC should always be at least 1, but we double check this
+     here.  This is also needed to silence -Werror-stringop
+     warnings.  */
+  gdb_assert (argc > 0);
+
+  if (startup_with_shell)
+    {
+#ifdef __MINGW32__
+      /* This holds all the characters considered special to the
+	 Windows shells.  */
+      static const char special[] = "\"!&*|[]{}<>?`~^=;, \t\n";
+      static const char quote = '"';
+#else
+      /* This holds all the characters considered special to the
+	 typical Unix shells.  We include `^' because the SunOS
+	 /bin/sh treats it as a synonym for `|'.  */
+      static const char special[] = "\"!#$&*()\\|[]{}<>?'`~^; \t\n";
+      static const char quote = '\'';
+#endif
+      int i;
+      int length = 0;
+      char *out, *cp;
+
+      /* We over-compute the size.  It shouldn't matter.  */
+      for (i = 0; i < argc; ++i)
+	length += 3 * strlen (argv[i]) + 1 + 2 * (argv[i][0] == '\0');
+
+      result = (char *) xmalloc (length);
+      out = result;
+
+      for (i = 0; i < argc; ++i)
+	{
+	  if (i > 0)
+	    *out++ = ' ';
+
+	  /* Need to handle empty arguments specially.  */
+	  if (argv[i][0] == '\0')
+	    {
+	      *out++ = quote;
+	      *out++ = quote;
+	    }
+	  else
+	    {
+#ifdef __MINGW32__
+	      int quoted = 0;
+
+	      if (strpbrk (argv[i], special))
+		{
+		  quoted = 1;
+		  *out++ = quote;
+		}
+#endif
+	      for (cp = argv[i]; *cp; ++cp)
+		{
+		  if (*cp == '\n')
+		    {
+		      /* A newline cannot be quoted with a backslash (it
+			 just disappears), only by putting it inside
+			 quotes.  */
+		      *out++ = quote;
+		      *out++ = '\n';
+		      *out++ = quote;
+		    }
+		  else
+		    {
+#ifdef __MINGW32__
+		      if (*cp == quote)
+#else
+		      if (strchr (special, *cp) != NULL)
+#endif
+			*out++ = '\\';
+		      *out++ = *cp;
+		    }
+		}
+#ifdef __MINGW32__
+	      if (quoted)
+		*out++ = quote;
+#endif
+	    }
+	}
+      *out = '\0';
+    }
+  else
+    {
+      /* In this case we can't handle arguments that contain spaces,
+	 tabs, or newlines -- see breakup_args().  */
+      int i;
+      int length = 0;
+
+      for (i = 0; i < argc; ++i)
+	{
+	  char *cp = strchr (argv[i], ' ');
+	  if (cp == NULL)
+	    cp = strchr (argv[i], '\t');
+	  if (cp == NULL)
+	    cp = strchr (argv[i], '\n');
+	  if (cp != NULL)
+	    error (_("can't handle command-line "
+		     "argument containing whitespace"));
+	  length += strlen (argv[i]) + 1;
+	}
+
+      result = (char *) xmalloc (length);
+      result[0] = '\0';
+      for (i = 0; i < argc; ++i)
+	{
+	  if (i > 0)
+	    strcat (result, " ");
+	  strcat (result, argv[i]);
+	}
+    }
+
+  return result;
+}
diff --git a/gdbsupport/common-inferior.h b/gdbsupport/common-inferior.h
index 3c8e87a..ee87bc7 100644
--- a/gdbsupport/common-inferior.h
+++ b/gdbsupport/common-inferior.h
@@ -58,4 +58,8 @@ extern void set_inferior_cwd (const char *cwd);
    the target is started up with a shell.  */
 extern bool startup_with_shell;
 
+/* Compute command-line string given argument vector. This does the
+   same shell processing as fork_inferior.  */
+extern char *construct_inferior_arguments (int, char **);
+
 #endif /* COMMON_COMMON_INFERIOR_H */