sysdb: Use a pager for displaying query results in interactive mode.

[sysdb.git] / src / tools / sysdb / command.c

diff --git a/src/tools/sysdb/command.c b/src/tools/sysdb/command.c
index 61960be83505ca167e4045f6a225854b9aeb0946..5888963ecf8ace7b7ee703d05a332a38bc0be353 100644 (file)
--- a/src/tools/sysdb/command.c
+++ b/src/tools/sysdb/command.c
@@ -40,12 +40,81 @@
 #include "utils/proto.h"
 #include "utils/strbuf.h"
 
+#include <sys/types.h>
+#include <sys/wait.h>
+
 #include <errno.h>
 
 #include <assert.h>
 #include <ctype.h>
+#include <signal.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
+
+static pid_t
+exec_pager(int in)
+{
+       pid_t pid;
+       long fd;
+
+       sigset_t sigs;
+
+       pid = fork();
+       if (pid) /* parent or error */
+               return pid;
+
+       sigemptyset(&sigs);
+       sigprocmask(SIG_SETMASK, &sigs, NULL);
+
+       for (fd = 3; fd <= sysconf(_SC_OPEN_MAX); fd++)
+               if (fd != in)
+                       close((int)fd);
+
+       if (dup2(in, STDIN_FILENO) >= 0) {
+               /* TODO: make configurable */
+               char *argv[] = { "less", "-FRX" };
+
+               close(in);
+               in = STDIN_FILENO;
+
+               if (execvp(argv[0], argv)) {
+                       char cmdbuf[1024], errbuf[1024];
+                       sdb_data_format(&(sdb_data_t){
+                                               SDB_TYPE_STRING | SDB_TYPE_ARRAY,
+                                               { .array = { SDB_STATIC_ARRAY_LEN(argv), argv } },
+                                       }, cmdbuf, sizeof(cmdbuf), SDB_UNQUOTED);
+                       sdb_log(SDB_LOG_WARNING, "Failed to execute pager %s: %s",
+                                       cmdbuf, sdb_strerror(errno, errbuf, sizeof(errbuf)));
+               }
+       }
+
+       /* else: something failed, simply print all input */
+       while (42) {
+               char buf[1024 + 1];
+               ssize_t n;
+
+               n = read(in, buf, sizeof(buf) - 1);
+               if (!n) /* EOF */
+                       break;
+
+               if (n > 0) {
+                       buf[n] = '\0';
+                       printf("%s", buf);
+                       continue;
+               }
+
+               if ((errno == EAGAIN) || (errno == EWOULDBLOCK)
+                               || (errno == EINTR))
+                       continue;
+
+               sdb_log(SDB_LOG_ERR, "Failed to read query result: %s",
+                               sdb_strerror(errno, buf, sizeof(buf)));
+               exit(1);
+       }
+       exit(0);
+} /* exec_pager */
 
 static void
 ok_printer(sdb_input_t __attribute__((unused)) *input, sdb_strbuf_t *buf)
@@ -73,11 +142,15 @@ log_printer(sdb_input_t __attribute__((unused)) *input, sdb_strbuf_t *buf)
 } /* log_printer */
 
 static void
-data_printer(sdb_input_t __attribute__((unused)) *input, sdb_strbuf_t *buf)
+data_printer(sdb_input_t *input, sdb_strbuf_t *buf)
 {
        size_t len = sdb_strbuf_len(buf);
        uint32_t type = 0;
 
+       int pipefd[2] = { -1, -1 };
+       FILE *out = stdout;
+       pid_t pager = -1;
+
        if ((! len) || (len == sizeof(uint32_t))) {
                /* empty command or empty reply */
                return;
@@ -88,11 +161,35 @@ data_printer(sdb_input_t __attribute__((unused)) *input, sdb_strbuf_t *buf)
                return;
        }
 
+       if (input->interactive) {
+               if (pipe(pipefd)) {
+                       char errbuf[2014];
+                       sdb_log(SDB_LOG_WARNING, "Failed to open pipe: %s",
+                                       sdb_strerror(errno, errbuf, sizeof(errbuf)));
+               }
+               else {
+                       out = fdopen(pipefd[1], "w");
+                       pager = exec_pager(pipefd[0]);
+                       if (pager < 0) {
+                               out = stdout;
+                               close(pipefd[0]);
+                               close(pipefd[1]);
+                       }
+                       else
+                               close(pipefd[0]);
+               }
+       }
+
        sdb_proto_unmarshal_int32(SDB_STRBUF_STR(buf), &type);
        sdb_strbuf_skip(buf, 0, sizeof(uint32_t));
-       if (sdb_json_print(input, (int)type, buf))
+       if (sdb_json_print(out, input, (int)type, buf))
                sdb_log(SDB_LOG_ERR, "Failed to print result");
-       printf("\n");
+       fprintf(out, "\n");
+
+       if (out != stdout)
+               fclose(out); /* will close pipefd[1] */
+       if (pager > 0)
+               waitpid(pager, NULL, 0);
 } /* data_printer */
 
 static struct {