Prepend every script with helpers.sh in runtime

Makefile

@@ -5,7 +5,7 @@ SRC := $(wildcard *.c)
 OBJ := $(SRC:.c=.o)
 DEP := $(OBJ:.o=.d)
 PRE := $(wildcard prev/*.sh)
-GEN := gen/prev/scripts.h gen/server.h
+GEN := gen/prev/scripts.h gen/server.h gen/helpers.h
 
 CFLAGS  += -Os -MD -Wall -Wextra -Wno-unused-parameter
 LDFLAGS += -lmagic -lcrypto
@@ -35,13 +35,17 @@ ctpv: $(OBJ)
 
 ctpv.c: $(GEN)
 
-gen/prev/scripts.h: $(PRE) embed/embed helpers.sh
+gen/prev/scripts.h: $(PRE) embed/embed
 	@mkdir -p $(@D)
-	embed/embed -p prev_scr_ -h helpers.sh $(PRE) > $@
+	embed/embed -p prev_scr_ $(PRE) > $@
 
-gen/server.h: clear.sh end.sh embed/embed helpers.sh
+gen/server.h: clear.sh end.sh embed/embed
 	@mkdir -p $(@D)
-	embed/embed -p scr_ -h helpers.sh clear.sh end.sh > $@
+	embed/embed -p scr_ clear.sh end.sh > $@
+
+gen/helpers.h: helpers.sh embed/embed
+	@mkdir -p $(@D)
+	embed/embed -p scr_ helpers.sh > $@
 
 embed/embed: make_embed
 	@:

preview.c

@@ -123,9 +123,11 @@ static int run(Preview *p, int *exitcode)
 
     int sp_arg[] = { pipe_fds[0], pipe_fds[1], STDERR_FILENO };
 
-    char *args[] = SHELL_ARGS(p->script);
+    char *script = prepend_helpers(p->script, p->script_len - 1);
+    char *args[] = SHELL_ARGS(script);
     int ret = spawn(args, NULL, exitcode, spawn_redirect, sp_arg);
 
+    free(script);
     close(pipe_fds[1]);
 
     if (*exitcode != FAILED_PREVIEW_EC) {

preview.h

@@ -6,6 +6,7 @@
 typedef struct {
     char *name, *ext, *type, *subtype, *script;
     int priority;
+    size_t script_len;
 } Preview;
 
 typedef struct {

previews.h

@@ -1,14 +1,16 @@
 #include <stdlib.h>
 #include <limits.h>
 
-#include "gen/prev/scripts.h"
+#include "utils.h"
 #include "preview.h"
+#include "gen/prev/scripts.h"
 
 /*
  * This file is supposed to be included in ctpv.c
  */
 
-#define PP(e, t, s, n, p) { #n, e, t, s, prev_scr_##n##_sh, p }
+#define PNAME(n) prev_scr_##n##_sh
+#define PP(e, t, s, n, p) { #n, e, t, s, PNAME(n), p, LEN(PNAME(n)) }
 #define PR(e, t, s, n) PP(e, t, s, n, 0)
 
 Preview previews[] = {
@@ -21,3 +23,5 @@ Preview previews[] = {
     PR(NULL,      "video",          NULL,             video),
     PR(NULL,      "application",    "pdf",            pdf),
 };
+
+/* vim: set nowrap: */

server.c

@@ -118,20 +118,26 @@ exit:
     return ret;
 }
 
+static int run_script(char *script, size_t script_len, char *arg)
+{
+    int ret = OK;
+
+    char *s = prepend_helpers(script, script_len);
+    char *args[] = SHELL_ARGS(s, arg);
+    int exitcode;
+    ERRCHK_GOTO_OK(spawn(args, NULL, &exitcode, NULL, NULL), ret, cleanup);
+
+cleanup:
+    free(s);
+    return ret;
+}
+
 int server_clear(void)
 {
-    char *args[] = SHELL_ARGS(scr_clear_sh);
-    int exitcode;
-    ERRCHK_RET_OK(spawn(args, NULL, &exitcode, NULL, NULL));
-
-    return OK;
+    return run_script(scr_clear_sh, LEN(scr_clear_sh)-1, "");
 }
 
 int server_end(const char *id_s)
 {
-    char *args[] = SHELL_ARGS(scr_end_sh, (char *)id_s);
-    int exitcode;
-    ERRCHK_RET_OK(spawn(args, NULL, &exitcode, NULL, NULL));
-
-    return OK;
+    return run_script(scr_end_sh, LEN(scr_end_sh)-1, (char *)id_s);
 }

shell.c

@@ -0,0 +1,34 @@
+#include <string.h>
+
+#include "shell.h"
+#include "error.h"
+#include "gen/helpers.h"
+
+/*
+ * Returns string with helpers.sh prepended
+ *
+ * User must call free()
+ */
+char *prepend_helpers(char *str, size_t len)
+{
+    char *buf, *b;
+    size_t mlen;
+
+    if (!(buf = malloc(sizeof(*buf) * (LEN(scr_helpers_sh) + len)))) {
+        PRINTINTERR(FUNCFAILED("malloc"), ERRNOS);
+        abort();
+    }
+
+    b = buf;
+    mlen = LEN(scr_helpers_sh);
+    memcpy(b, scr_helpers_sh, mlen);
+
+    b += (mlen - 1) * sizeof(*str);
+    mlen = len;
+    memcpy(b, str, mlen);
+
+    b += mlen * sizeof(*str);
+    b[0] = '\0';
+
+    return buf;
+}

shell.h

@@ -1,7 +1,11 @@
 #ifndef SHELL_H
 #define SHELL_H
 
+#include "utils.h"
+
 #define SHELL_ARGS(script, ...) \
-    { "sh", "-c", script, "sh", __VA_ARGS__ __VA_OPT__(,) NULL }
+    { "/bin/sh", "-c", script, "/bin/sh", __VA_ARGS__ __VA_OPT__(,) NULL }
+
+char *prepend_helpers(char *str, size_t len);
 
 #endif