feat: add native JSON output (-J/-j flags)

Lsof.8

@@ -900,6 +900,47 @@ When specified without a PGID set that's all it does.
 .B \-H
 directs lsof to print human readable sizes, e.g. 123.4K 456.7M.
 .TP \w'names'u+4
+.B \-J
+selects JSON output mode.  Instead of the traditional tabular or
+.B \-F
+field output, lsof produces a single JSON object on stdout containing
+a
+.B "processes"
+array.  Each process object contains its fields and a
+.B "files"
+array of open file entries.
+.IP
+Field selection follows the same rules as
+.BR \-F :
+use
+.B \-F
+with field characters to select which fields appear in the JSON output.
+Without
+.BR \-F ,
+the default field set is used.
+.IP
+.B \-J
+is mutually exclusive with
+.B \-j
+and
+.BR \-t .
+Warnings and errors are sent to stderr; stdout is always valid JSON.
+.TP \w'names'u+4
+.B \-j
+selects JSON Lines output mode.  Each open file produces one JSON
+object per line, combining process and file fields in a single
+denormalized record.  This format is suitable for streaming pipelines,
+log ingestion (Splunk, Datadog, Elastic), and line\-oriented tools.
+.IP
+Field selection follows the same rules as
+.BR \-J .
+.IP
+.B \-j
+is mutually exclusive with
+.B \-J
+and
+.BR \-t .
+.TP \w'names'u+4
 .BI \-i " [i]"
 selects the listing of files any of whose Internet address
 matches the address specified in \fIi\fP.

Makefile.am

@@ -132,7 +132,9 @@ DIALECT_NEUTRAL_TESTS = tests/case-00-hello.bash \
 	tests/case-20-offset-field.bash \
 	tests/case-20-repeat-count.bash \
 	tests/case-21-exit-Q-status.bash \
-	tests/case-22-empty-process-name.bash
+	tests/case-22-empty-process-name.bash \
+	tests/case-30-json-output.bash \
+	tests/case-31-jsonl-output.bash
 TESTS = $(DIALECT_NEUTRAL_TESTS)
 EXTRA_DIST += $(DIALECT_NEUTRAL_TESTS) \
 	tests/case-13-classic.bash \

lib/common.h

@@ -684,6 +684,9 @@ extern int ErrStat;
 extern uid_t Euid;
 extern int Fcntx;
 extern int Ffield;
+extern int Fjson;
+extern int Fjsonl;
+extern int Fjson_first_proc;
 extern int Ffilesys;
 extern int Fhelp;
 extern int Fhost;

lib/dialects/aix/Makefile

@@ -155,7 +155,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 

lib/dialects/darwin/Makefile

@@ -162,7 +162,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 

lib/dialects/freebsd/Makefile

@@ -141,7 +141,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 

lib/dialects/hpux/kmem/Makefile

@@ -147,7 +147,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 

lib/dialects/hpux/pstat/Makefile

@@ -136,7 +136,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 

lib/dialects/linux/Makefile

@@ -167,7 +167,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 

lib/dialects/netbsd/Makefile

@@ -145,7 +145,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 

lib/dialects/openbsd/Makefile

@@ -145,7 +145,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 

lib/dialects/osr/Makefile

@@ -151,7 +151,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 

lib/dialects/sun/Makefile

@@ -146,7 +146,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 

lib/dialects/uw/Makefile

@@ -145,7 +145,7 @@ misc.o:		${HDR} misc.c
 
 node.o:		${HDR} node.c
 
-print.o:	${HDR} print.c
+print.o:	${HDR} version.h print.c
 
 proc.o:		${HDR} proc.c
 

lib/proto.h

@@ -187,6 +187,8 @@ extern void print_init(struct lsof_context *ctx);
 extern void printname(struct lsof_context *ctx, int nl);
 extern char *print_kptr(KA_T kp, char *buf, size_t bufl);
 extern int print_proc(struct lsof_context *ctx);
+extern void json_open_envelope(void);
+extern void json_close_envelope(void);
 extern void fd_to_string(enum lsof_fd_type fd_type, int fd_num, char *buf);
 extern void printrawaddr(struct lsof_context *ctx, struct sockaddr *sa);
 extern void print_tcptpi(struct lsof_context *ctx, int nl);

src/main.c

@@ -47,6 +47,58 @@ static int GetOpt(struct lsof_context *ctx, int ct, char *opt[], char *rules,
                   int *err);
 static char *sv_fmt_str(struct lsof_context *ctx, char *f);
 
+/*
+ * select_default_fields() - enable the default set of FieldSel entries
+ *
+ * Shared by -F (with no field chars) and -J/-j (when no -F given).
+ */
+static void select_default_fields(void) {
+    int i;
+    for (i = 0; FieldSel[i].nm; i++) {
+
+#if !defined(HASPPID)
+        if (FieldSel[i].id == LSOF_FID_PPID)
+            continue;
+#endif /* !defined(HASPPID) */
+
+#if !defined(HASTASKS)
+        if (FieldSel[i].id == LSOF_FID_TCMD)
+            continue;
+#endif /* !defined(HASTASKS) */
+
+#if !defined(HASFSTRUCT)
+        if (FieldSel[i].id == LSOF_FID_CT || FieldSel[i].id == LSOF_FID_FA ||
+            FieldSel[i].id == LSOF_FID_FG || FieldSel[i].id == LSOF_FID_NI)
+            continue;
+#endif /* !defined(HASFSTRUCT) */
+
+#if defined(HASSELINUX)
+        if ((FieldSel[i].id == LSOF_FID_CNTX) && !CntxStatus)
+            continue;
+#else  /* !defined(HASSELINUX) */
+        if (FieldSel[i].id == LSOF_FID_CNTX)
+            continue;
+#endif /* !defined(HASSELINUX) */
+
+        if (FieldSel[i].id == LSOF_FID_RDEV)
+            continue; /* for compatibility */
+
+#if !defined(HASTASKS)
+        if (FieldSel[i].id == LSOF_FID_TID)
+            continue;
+#endif /* !defined(HASTASKS) */
+
+#if !defined(HASZONES)
+        if (FieldSel[i].id == LSOF_FID_ZONE)
+            continue;
+#endif /* !defined(HASZONES) */
+
+        FieldSel[i].st = 1;
+        if (FieldSel[i].opt && FieldSel[i].ov)
+            *(FieldSel[i].opt) |= FieldSel[i].ov;
+    }
+}
+
 /*
  * main() - main function for lsof
  */
@@ -151,7 +203,7 @@ int main(int argc, char *argv[]) {
      * Create option mask.
      */
     (void)snpf(options, sizeof(options),
-               "?a%sbc:%sD:d:%s%sf:F:g:hHi:%s%slL:%s%snNo:Op:QPr:%ss:S:tT:u:"
+               "?a%sbc:%sD:d:%s%sf:F:g:hHi:%s%sJjlL:%s%snNo:Op:QPr:%ss:S:tT:u:"
                "UvVwx:%s%s%s",
 
 #if defined(HAS_AFS) && defined(HASAOPT)
@@ -429,51 +481,7 @@ int main(int argc, char *argv[]) {
                     } else if (*GOv == '0')
                         Terminator = '\0';
                 }
-                for (i = 0; FieldSel[i].nm; i++) {
-
-#if !defined(HASPPID)
-                    if (FieldSel[i].id == LSOF_FID_PPID)
-                        continue;
-#endif /* !defined(HASPPID) */
-
-#if !defined(HASTASKS)
-                    if (FieldSel[i].id == LSOF_FID_TCMD)
-                        continue;
-#endif /* !defined(HASTASKS) */
-
-#if !defined(HASFSTRUCT)
-                    if (FieldSel[i].id == LSOF_FID_CT ||
-                        FieldSel[i].id == LSOF_FID_FA ||
-                        FieldSel[i].id == LSOF_FID_FG ||
-                        FieldSel[i].id == LSOF_FID_NI)
-                        continue;
-#endif /* !defined(HASFSTRUCT) */
-
-#if defined(HASSELINUX)
-                    if ((FieldSel[i].id == LSOF_FID_CNTX) && !CntxStatus)
-                        continue;
-#else  /* !defined(HASSELINUX) */
-                    if (FieldSel[i].id == LSOF_FID_CNTX)
-                        continue;
-#endif /* !defined(HASSELINUX) */
-
-                    if (FieldSel[i].id == LSOF_FID_RDEV)
-                        continue; /* for compatibility */
-
-#if !defined(HASTASKS)
-                    if (FieldSel[i].id == LSOF_FID_TID)
-                        continue;
-#endif /* !defined(HASTASKS) */
-
-#if !defined(HASZONES)
-                    if (FieldSel[i].id == LSOF_FID_ZONE)
-                        continue;
-#endif /* !defined(HASZONES) */
-
-                    FieldSel[i].st = 1;
-                    if (FieldSel[i].opt && FieldSel[i].ov)
-                        *(FieldSel[i].opt) |= FieldSel[i].ov;
-                }
+                select_default_fields();
 
 #if defined(HASFSTRUCT)
                 Ffield = FsvFlagX = 1;
@@ -556,6 +564,24 @@ int main(int argc, char *argv[]) {
         case '?':
             Fhelp = 1;
             break;
+        case 'J':
+            if (GOp == '+') {
+                (void)fprintf(stderr, "%s: +J is not supported\n", Pn);
+                err = 1;
+                break;
+            }
+            Fjson = 1;
+            Ffield = 1;
+            break;
+        case 'j':
+            if (GOp == '+') {
+                (void)fprintf(stderr, "%s: +j is not supported\n", Pn);
+                err = 1;
+                break;
+            }
+            Fjsonl = 1;
+            Ffield = 1;
+            break;
         case 'i':
             if (!GOv || *GOv == '-' || *GOv == '+') {
                 Fnet = 1;
@@ -1097,6 +1123,14 @@ int main(int argc, char *argv[]) {
         (void)fprintf(stderr, "%s: -x must accompany +d or +D\n", Pn);
         err++;
     }
+    if (Fjson && Fjsonl) {
+        (void)fprintf(stderr, "%s: -J and -j are mutually exclusive\n", Pn);
+        err++;
+    }
+    if ((Fjson || Fjsonl) && Fterse) {
+        (void)fprintf(stderr, "%s: -J/-j and -t are mutually exclusive\n", Pn);
+        err++;
+    }
 
 #if defined(HASEOPT)
     if (Efsysl) {
@@ -1126,6 +1160,24 @@ int main(int argc, char *argv[]) {
     }
 #endif /* defined(HASEOPT) */
 
+    /*
+     * If -J/-j was given, ensure field selections are set.
+     * If -F was also given with field chars, those selections are already
+     * in FieldSel[]. Otherwise, enable the default field set.
+     */
+    if (Fjson || Fjsonl) {
+        int has_fields = 0;
+        for (i = 0; FieldSel[i].nm; i++) {
+            if (FieldSel[i].st && FieldSel[i].id != LSOF_FID_PID &&
+                FieldSel[i].id != LSOF_FID_MARK) {
+                has_fields = 1;
+                break;
+            }
+        }
+        if (!has_fields)
+            select_default_fields();
+    }
+
     if (DChelp || err || Fhelp || fh || version)
         usage(ctx, err ? 1 : 0, fh, version);
     /*
@@ -1312,6 +1364,9 @@ int main(int argc, char *argv[]) {
             (void)qsort((QSORT_P *)slp, (size_t)Nlproc,
                         (size_t)sizeof(struct lproc *), comppid);
         }
+        if (Fjson) {
+            json_open_envelope();
+        }
         if ((n = Nlproc)) {
 
 #if defined(HASNCACHE)
@@ -1468,6 +1523,11 @@ int main(int argc, char *argv[]) {
             }
             Lf = lf;
         }
+        if (Fjson) {
+            json_close_envelope();
+        } else if (Fjsonl && RptTm) {
+            putchar('\n');
+        }
         /*
          * If a repeat time is set, sleep for the specified time.
          *
@@ -1515,7 +1575,9 @@ int main(int argc, char *argv[]) {
             }
 #endif /* defined(HAS_STRFTIME) */
 
-            if (Ffield) {
+            if (Fjson || Fjsonl) {
+                /* JSON modes handle their own cycle separation */
+            } else if (Ffield) {
                 putchar(LSOF_FID_MARK);
 
 #if defined(HAS_STRFTIME)