[PATCH 09/30] kconfig: add 'shell' built-in function

[Masahiro Yamada]

This accepts a single command to execute.  It returns the standard
output from it.

[Example code]

  config HELLO
  string
  default "$(shell echo hello world)"

  config Y
  def_bool $(shell echo y)

[Result]

  $ make -s alldefconfig && tail -n 2 .config
  CONFIG_HELLO="hello world"
  CONFIG_Y=y

Caveat:
Like environments, functions are expanded in the lexer.  You cannot
pass symbols to function arguments.  This is a limitation to simplify
the implementation.  I want to avoid the dynamic function evaluation,
which would introduce much more complexity.

Signed-off-by: Masahiro Yamada 
---

Changes in v3: None
Changes in v2: None

 scripts/kconfig/preprocess.c | 66 
 1 file changed, 66 insertions(+)

diff --git a/scripts/kconfig/preprocess.c b/scripts/kconfig/preprocess.c
index e77cf7c..f4c606f 100644
--- a/scripts/kconfig/preprocess.c
+++ b/scripts/kconfig/preprocess.c
@@ -86,7 +86,73 @@ struct function {
char *(*func)(int argc, char *argv[]);
 };
 
+/*
+ * Some commands treats commas verbatim.  Concatenate arguments to get
+ * back the original input.  The returned string must be freed when done.
+ */
+static char *join_args(int argc, char *argv[])
+{
+   size_t len = 0;
+   char *out;
+   int i;
+
+   for (i = 0; i < argc; i++)
+   len += strlen(argv[i]) + 1;
+
+   out = xmalloc(len);
+   out[0] = 0;
+   for (i = 0; i < argc; i++) {
+   strcat(out, argv[i]);
+   if (i != argc - 1)
+   strcat(out, ",");
+   }
+
+   return out;
+}
+
+static char *do_shell(int argc, char *argv[])
+{
+   FILE *p;
+   char buf[256];
+   char *cmd;
+   size_t nread;
+   int i;
+
+   cmd = join_args(argc, argv);
+
+   p = popen(cmd, "r");
+   if (!p) {
+   perror(cmd);
+   goto free;
+   }
+
+   nread = fread(buf, 1, sizeof(buf), p);
+   if (nread == sizeof(buf))
+   nread--;
+
+   /* remove trailing new lines */
+   while (buf[nread - 1] == '\n')
+   nread--;
+
+   buf[nread] = 0;
+
+   /* replace a new line with a space */
+   for (i = 0; i < nread; i++) {
+   if (buf[i] == '\n')
+   buf[i] = ' ';
+   }
+
+   if (pclose(p) == -1)
+   perror(cmd);
+
+free:
+   free(cmd);
+
+   return xstrdup(buf);
+}
+
 static const struct function function_table[] = {
+   { .name = "shell", .func = do_shell },
 };
 
 static char *function_call(const char *name, int argc, char *argv[])
-- 
2.7.4

[PATCH 09/30] kconfig: add 'shell' built-in function

[Masahiro Yamada]

This accepts a single command to execute.  It returns the standard
output from it.

[Example code]

  config HELLO
  string
  default "$(shell echo hello world)"

  config Y
  def_bool $(shell echo y)

[Result]

  $ make -s alldefconfig && tail -n 2 .config
  CONFIG_HELLO="hello world"
  CONFIG_Y=y

Caveat:
Like environments, functions are expanded in the lexer.  You cannot
pass symbols to function arguments.  This is a limitation to simplify
the implementation.  I want to avoid the dynamic function evaluation,
which would introduce much more complexity.

Signed-off-by: Masahiro Yamada 
---

Changes in v3: None
Changes in v2: None

 scripts/kconfig/preprocess.c | 66 
 1 file changed, 66 insertions(+)

diff --git a/scripts/kconfig/preprocess.c b/scripts/kconfig/preprocess.c
index e77cf7c..f4c606f 100644
--- a/scripts/kconfig/preprocess.c
+++ b/scripts/kconfig/preprocess.c
@@ -86,7 +86,73 @@ struct function {
char *(*func)(int argc, char *argv[]);
 };
 
+/*
+ * Some commands treats commas verbatim.  Concatenate arguments to get
+ * back the original input.  The returned string must be freed when done.
+ */
+static char *join_args(int argc, char *argv[])
+{
+   size_t len = 0;
+   char *out;
+   int i;
+
+   for (i = 0; i < argc; i++)
+   len += strlen(argv[i]) + 1;
+
+   out = xmalloc(len);
+   out[0] = 0;
+   for (i = 0; i < argc; i++) {
+   strcat(out, argv[i]);
+   if (i != argc - 1)
+   strcat(out, ",");
+   }
+
+   return out;
+}
+
+static char *do_shell(int argc, char *argv[])
+{
+   FILE *p;
+   char buf[256];
+   char *cmd;
+   size_t nread;
+   int i;
+
+   cmd = join_args(argc, argv);
+
+   p = popen(cmd, "r");
+   if (!p) {
+   perror(cmd);
+   goto free;
+   }
+
+   nread = fread(buf, 1, sizeof(buf), p);
+   if (nread == sizeof(buf))
+   nread--;
+
+   /* remove trailing new lines */
+   while (buf[nread - 1] == '\n')
+   nread--;
+
+   buf[nread] = 0;
+
+   /* replace a new line with a space */
+   for (i = 0; i < nread; i++) {
+   if (buf[i] == '\n')
+   buf[i] = ' ';
+   }
+
+   if (pclose(p) == -1)
+   perror(cmd);
+
+free:
+   free(cmd);
+
+   return xstrdup(buf);
+}
+
 static const struct function function_table[] = {
+   { .name = "shell", .func = do_shell },
 };
 
 static char *function_call(const char *name, int argc, char *argv[])
-- 
2.7.4