bc: hook up line editing with history buffer

function                                             old     new   delta
push_input_byte                                        -      65     +65
bc_vm_run                                           1875    1905     +30
bc_read_line                                         303     305      +2
bc_num_binary                                        148     150      +2
bc_num_ulong                                         103      92     -11
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 3/1 up/down: 99/-11)             Total: 88 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 63 insertions, 25 deletions

diff --git a/miscutils/bc.c b/miscutils/bc.c
index 90c3bf5d6..dc4fa37a4 100644
--- a/miscutils/bc.c
+++ b/miscutils/bc.c
@@ -167,6 +167,7 @@
 //usage:       "64\n"
 
 #include "libbb.h"
+#include "common_bufsiz.h"
 
 typedef enum BcStatus {
         BC_STATUS_SUCCESS = 0,
@@ -750,6 +751,10 @@ struct globals {
         BcVec files;
 
         char *env_args;
+
+#if ENABLE_FEATURE_EDITING
+        line_input_t *line_input_state;
+#endif
 } FIX_ALIASING;
 #define G (*ptr_to_globals)
 #define INIT_G() do { \
@@ -974,9 +979,9 @@ static NOINLINE int bc_posix_error_fmt(const char *fmt, ...)
 
 // We use error functions with "return bc_error(FMT[, PARAMS])" idiom.
 // This idiom begs for tail-call optimization, but for it to work,
-// function must not have calller-cleaned parameters on stack.
-// Unfortunately, vararg functions do exactly that on most arches.
-// Thus, these shims for the cases when we have no PARAMS:
+// function must not have caller-cleaned parameters on stack.
+// Unfortunately, vararg function API does exactly that on most arches.
+// Thus, use these shims for the cases when we have no vararg PARAMS:
 static int bc_error(const char *msg)
 {
         return bc_error_fmt("%s", msg);
@@ -1195,17 +1200,33 @@ static size_t bc_map_index(const BcVec *v, const void *ptr)
         return bc_id_cmp(ptr, bc_vec_item(v, i)) ? BC_VEC_INVALID_IDX : i;
 }
 
+static int push_input_byte(BcVec *vec, char c)
+{
+        if ((c < ' ' && c != '\t' && c != '\r' && c != '\n') // also allow '\v' '\f'?
+         || c > 0x7e
+        ) {
+                // Bad chars on this line, ignore entire line
+                bc_error_fmt("illegal character 0x%02x", c);
+                return 1;
+        }
+        bc_vec_pushByte(vec, (char)c);
+        return 0;
+}
+
 static BcStatus bc_read_line(BcVec *vec, const char *prompt)
 {
         bool bad_chars;
 
+        if (G_posix) prompt = "";
+
         do {
-                int i;
+                int c;
 
                 bad_chars = 0;
                 bc_vec_pop_all(vec);
 
                 fflush_and_check();
+
 #if ENABLE_FEATURE_BC_SIGNALS
                 if (bb_got_signal) { // ^C was pressed
  intr:
@@ -1215,23 +1236,42 @@ static BcStatus bc_read_line(BcVec *vec, const char *prompt)
                                 : "\ninterrupt (type \"q\" to exit)\n"
                                 , stderr);
                 }
+# if ENABLE_FEATURE_EDITING
+                if (G_ttyin) {
+                        int n, i;
+#  define line_buf bb_common_bufsiz1
+                        n = read_line_input(G.line_input_state, prompt, line_buf, COMMON_BUFSIZE);
+                        if (n <= 0) { // read errors or EOF, or ^D, or ^C
+                                if (n == 0) // ^C
+                                        goto intr;
+                                G.eof = 1;
+                                break;
+                        }
+                        i = 0;
+                        for (;;) {
+                                c = line_buf[i++];
+                                if (!c) break;
+                                bad_chars |= push_input_byte(vec, c);
+                        }
+#  undef line_buf
+                } else
+# endif
 #endif
                 {
-                        if (G_ttyin && !G_posix)
+                        if (G_ttyin)
                                 fputs(prompt, stderr);
-
                         IF_FEATURE_BC_SIGNALS(errno = 0;)
                         do {
-                                i = fgetc(stdin);
-                                if (i == EOF) {
-#if ENABLE_FEATURE_BC_SIGNALS
-                                        // Both conditions appear simultaneously, check both just in case
-                                        if (errno == EINTR || bb_got_signal) {
-                                                // ^C was pressed
-                                                clearerr(stdin);
-                                                goto intr;
-                                        }
+                                c = fgetc(stdin);
+#if ENABLE_FEATURE_BC_SIGNALS && !ENABLE_FEATURE_EDITING
+                                // Both conditions appear simultaneously, check both just in case
+                                if (errno == EINTR || bb_got_signal) {
+                                        // ^C was pressed
+                                        clearerr(stdin);
+                                        goto intr;
+                                }
 #endif
+                                if (c == EOF) {
                                         if (ferror(stdin))
                                                 quit(); // this emits error message
                                         G.eof = 1;
@@ -1240,16 +1280,8 @@ static BcStatus bc_read_line(BcVec *vec, const char *prompt)
                                         // printf 'print 123' | bc   - fails (syntax error)
                                         break;
                                 }
-
-                                if ((i < ' ' && i != '\t' && i != '\r' && i != '\n') // also allow '\v' '\f'?
-                                 || i > 0x7e
-                                ) {
-                                        // Bad chars on this line, ignore entire line
-                                        bc_error_fmt("illegal character 0x%02x", i);
-                                        bad_chars = 1;
-                                }
-                                bc_vec_pushByte(vec, (char)i);
-                        } while (i != '\n');
+                                bad_chars |= push_input_byte(vec, c);
+                        } while (c != '\n');
                 }
         } while (bad_chars);
 
@@ -7391,6 +7423,9 @@ static BcStatus bc_vm_run(char **argv, const char *env_len)
 {
         BcStatus st;
 
+#if ENABLE_FEATURE_EDITING
+        G.line_input_state = new_line_input_t(DO_HISTORY);
+#endif
         G.prog.len = bc_vm_envLen(env_len);
 
         bc_vm_init();
@@ -7425,6 +7460,9 @@ static BcStatus bc_vm_run(char **argv, const char *env_len)
 
 #if ENABLE_FEATURE_CLEAN_UP
         bc_vm_free();
+# if ENABLE_FEATURE_EDITING
+        free_line_input_t(G.line_input_state);
+# endif
         FREE_G();
 #endif
         return st;