Add JSON coercion support for non-JSON plist types

- Add PLIST_OPT_COERCE option to coerce PLIST_DATE, PLIST_DATA, and PLIST_UID to JSON-compatible types (ISO 8601 strings, Base64 strings, and integers)
- Add plist_to_json_with_options() function to allow passing coercion options (and others)
- Update plist_write_to_string() and plist_write_to_stream() to support coercion option
- Add --coerce flag to plistutil for JSON output
- Create plist2json symlink that automatically enables coercion when invoked

Author: calilkhalil

include/plist/plist.h

@@ -175,6 +175,11 @@ extern "C"
         PLIST_OPT_PARTIAL_DATA = 1 << 1, /**< Print 24 bytes maximum of #PLIST_DATA values. If the data is longer than 24 bytes,  the first 16 and last 8 bytes will be written. Only valid for #PLIST_FORMAT_PRINT. */
         PLIST_OPT_NO_NEWLINE = 1 << 2, /**< Do not print a final newline character. Only valid for #PLIST_FORMAT_PRINT, #PLIST_FORMAT_LIMD, and #PLIST_FORMAT_PLUTIL. */
         PLIST_OPT_INDENT = 1 << 3, /**< Indent each line of output. Currently only #PLIST_FORMAT_PRINT and #PLIST_FORMAT_LIMD are supported. Use #PLIST_OPT_INDENT_BY() macro to specify the level of indentation. */
+        PLIST_OPT_COERCE = 1 << 4, /**< Coerce plist types that have no native JSON representation into JSON-compatible types.
+                                        #PLIST_DATE is converted to an ISO 8601 date string,
+                                        #PLIST_DATA is converted to a Base64-encoded string, and
+                                        #PLIST_UID is converted to an integer.
+                                        Only valid for #PLIST_FORMAT_JSON. Without this option, these types cause #PLIST_ERR_FORMAT. */
     } plist_write_options_t;
 
     /** To be used with #PLIST_OPT_INDENT - encodes the level of indentation for OR'ing it into the #plist_write_options_t bitfield. */
@@ -937,6 +942,29 @@ extern "C"
      */
     PLIST_API plist_err_t plist_to_json(plist_t plist, char **plist_json, uint32_t* length, int prettify);
 
+    /**
+     * Export the #plist_t structure to JSON format with extended options.
+     *
+     * When \a PLIST_OPT_COMPACT is set in \a options, the resulting JSON
+     * will be non-prettified.
+     *
+     * When \a PLIST_OPT_COERCE is set in \a options, plist types that have
+     * no native JSON representation are converted to JSON-compatible types
+     * instead of returning #PLIST_ERR_FORMAT:
+     * - #PLIST_DATE is serialized as an ISO 8601 date string
+     * - #PLIST_DATA is serialized as a Base64-encoded string
+     * - #PLIST_UID is serialized as an integer
+     *
+     * @param plist the root node to export
+     * @param plist_json a pointer to a char* buffer. This function allocates the memory,
+     *     caller is responsible for freeing it.
+     * @param length a pointer to an uint32_t variable. Represents the length of the allocated buffer.
+     * @param options One or more bitwise ORed values of #plist_write_options_t.
+     * @return PLIST_ERR_SUCCESS on success or a #plist_err_t on failure
+     * @note Use plist_mem_free() to free the allocated memory.
+     */
+    PLIST_API plist_err_t plist_to_json_with_options(plist_t plist, char **plist_json, uint32_t* length, plist_write_options_t options);
+
     /**
      * Export the #plist_t structure to OpenStep format.
      *

src/jplist.c

@@ -39,6 +39,10 @@
 #include "strbuf.h"
 #include "jsmn.h"
 #include "hashtable.h"
+#include "base64.h"
+#include "time64.h"
+
+#define MAC_EPOCH 978307200
 
 #ifdef DEBUG
 static int plist_json_debug = 0;
@@ -115,7 +119,7 @@ static size_t dtostr(char *buf, size_t bufsize, double realval)
     return len;
 }
 
-static plist_err_t node_to_json(node_t node, bytearray_t **outbuf, uint32_t depth, int prettify)
+static plist_err_t node_to_json(node_t node, bytearray_t **outbuf, uint32_t depth, int prettify, int coerce)
 {
     plist_data_t node_data = NULL;
 
@@ -211,7 +215,7 @@ static plist_err_t node_to_json(node_t node, bytearray_t **outbuf, uint32_t dept
                     str_buf_append(*outbuf, "  ", 2);
                 }
             }
-            plist_err_t res = node_to_json(ch, outbuf, depth+1, prettify);
+            plist_err_t res = node_to_json(ch, outbuf, depth+1, prettify, coerce);
             if (res < 0) {
                 return res;
             }
@@ -239,7 +243,7 @@ static plist_err_t node_to_json(node_t node, bytearray_t **outbuf, uint32_t dept
                     str_buf_append(*outbuf, "  ", 2);
                 }
             }
-            plist_err_t res = node_to_json(ch, outbuf, depth+1, prettify);
+            plist_err_t res = node_to_json(ch, outbuf, depth+1, prettify, coerce);
             if (res < 0) {
                 return res;
             }
@@ -260,17 +264,60 @@ static plist_err_t node_to_json(node_t node, bytearray_t **outbuf, uint32_t dept
         str_buf_append(*outbuf, "}", 1);
         } break;
     case PLIST_DATA:
-        // NOT VALID FOR JSON
-        PLIST_JSON_WRITE_ERR("PLIST_DATA type is not valid for JSON format\n");
-        return PLIST_ERR_FORMAT;
+        if (coerce) {
+            size_t b64_len = ((node_data->length + 2) / 3) * 4;
+            char *b64_buf = (char*)malloc(b64_len + 1);
+            if (!b64_buf) {
+                return PLIST_ERR_NO_MEM;
+            }
+            size_t actual_len = base64encode(b64_buf, node_data->buff, node_data->length);
+            str_buf_append(*outbuf, "\"", 1);
+            str_buf_append(*outbuf, b64_buf, actual_len);
+            str_buf_append(*outbuf, "\"", 1);
+            free(b64_buf);
+        } else {
+            PLIST_JSON_WRITE_ERR("PLIST_DATA type is not valid for JSON format\n");
+            return PLIST_ERR_FORMAT;
+        }
+        break;
     case PLIST_DATE:
-        // NOT VALID FOR JSON
-        PLIST_JSON_WRITE_ERR("PLIST_DATE type is not valid for JSON format\n");
-        return PLIST_ERR_FORMAT;
+        if (coerce) {
+            Time64_T timev = (Time64_T)node_data->realval + MAC_EPOCH;
+            struct TM _btime;
+            struct TM *btime = gmtime64_r(&timev, &_btime);
+            char datebuf[32];
+            size_t datelen = 0;
+            if (btime) {
+                struct tm _tmcopy;
+                copy_TM64_to_tm(btime, &_tmcopy);
+                datelen = strftime(datebuf, sizeof(datebuf), "%Y-%m-%dT%H:%M:%SZ", &_tmcopy);
+            }
+            if (datelen <= 0) {
+                datelen = snprintf(datebuf, sizeof(datebuf), "1970-01-01T00:00:00Z");
+            }
+            str_buf_append(*outbuf, "\"", 1);
+            str_buf_append(*outbuf, datebuf, datelen);
+            str_buf_append(*outbuf, "\"", 1);
+        } else {
+            PLIST_JSON_WRITE_ERR("PLIST_DATE type is not valid for JSON format\n");
+            return PLIST_ERR_FORMAT;
+        }
+        break;
     case PLIST_UID:
-        // NOT VALID FOR JSON
-        PLIST_JSON_WRITE_ERR("PLIST_UID type is not valid for JSON format\n");
-        return PLIST_ERR_FORMAT;
+        if (coerce) {
+            val = (char*)malloc(64);
+            if (node_data->length == 16) {
+                val_len = snprintf(val, 64, "%" PRIu64, node_data->intval);
+            } else {
+                val_len = snprintf(val, 64, "%" PRIi64, node_data->intval);
+            }
+            str_buf_append(*outbuf, val, val_len);
+            free(val);
+        } else {
+            PLIST_JSON_WRITE_ERR("PLIST_UID type is not valid for JSON format\n");
+            return PLIST_ERR_FORMAT;
+        }
+        break;
     default:
         return PLIST_ERR_UNKNOWN;
     }
@@ -316,7 +363,7 @@ static int num_digits_u(uint64_t i)
     return n;
 }
 
-static plist_err_t _node_estimate_size(node_t node, uint64_t *size, uint32_t depth, int prettify, hashtable_t *visited)
+static plist_err_t _node_estimate_size(node_t node, uint64_t *size, uint32_t depth, int prettify, int coerce, hashtable_t *visited)
 {
     plist_data_t data;
     if (!node) {
@@ -341,7 +388,7 @@ static plist_err_t _node_estimate_size(node_t node, uint64_t *size, uint32_t dep
         node_t ch;
         unsigned int n_children = node_n_children(node);
         for (ch = node_first_child(node); ch; ch = node_next_sibling(ch)) {
-            plist_err_t res = _node_estimate_size(ch, size, depth + 1, prettify, visited);
+            plist_err_t res = _node_estimate_size(ch, size, depth + 1, prettify, coerce, visited);
             if (res < 0) {
                 return res;
             }
@@ -398,17 +445,36 @@ static plist_err_t _node_estimate_size(node_t node, uint64_t *size, uint32_t dep
             *size += 2;
             break;
         case PLIST_DATA:
-            // NOT VALID FOR JSON
-            PLIST_JSON_WRITE_ERR("PLIST_DATA type is not valid for JSON format\n");
-            return PLIST_ERR_FORMAT;
+            if (coerce) {
+                // base64 encoded string: 2 quotes + ((len+2)/3)*4 base64 chars
+                *size += 2 + ((data->length + 2) / 3) * 4;
+            } else {
+                PLIST_JSON_WRITE_ERR("PLIST_DATA type is not valid for JSON format\n");
+                return PLIST_ERR_FORMAT;
+            }
+            break;
         case PLIST_DATE:
-            // NOT VALID FOR JSON
-            PLIST_JSON_WRITE_ERR("PLIST_DATE type is not valid for JSON format\n");
-            return PLIST_ERR_FORMAT;
+            if (coerce) {
+                // ISO 8601 string: "YYYY-MM-DDTHH:MM:SSZ" = 22 chars max
+                *size += 24;
+            } else {
+                PLIST_JSON_WRITE_ERR("PLIST_DATE type is not valid for JSON format\n");
+                return PLIST_ERR_FORMAT;
+            }
+            break;
         case PLIST_UID:
-            // NOT VALID FOR JSON
-            PLIST_JSON_WRITE_ERR("PLIST_UID type is not valid for JSON format\n");
-            return PLIST_ERR_FORMAT;
+            if (coerce) {
+                // integer representation
+                if (data->length == 16) {
+                    *size += num_digits_u(data->intval);
+                } else {
+                    *size += num_digits_i((int64_t)data->intval);
+                }
+            } else {
+                PLIST_JSON_WRITE_ERR("PLIST_UID type is not valid for JSON format\n");
+                return PLIST_ERR_FORMAT;
+            }
+            break;
         default:
             PLIST_JSON_WRITE_ERR("invalid node type encountered\n");
             return PLIST_ERR_UNKNOWN;
@@ -417,16 +483,22 @@ static plist_err_t _node_estimate_size(node_t node, uint64_t *size, uint32_t dep
     return PLIST_ERR_SUCCESS;
 }
 
-static plist_err_t node_estimate_size(node_t node, uint64_t *size, uint32_t depth, int prettify)
+static plist_err_t node_estimate_size(node_t node, uint64_t *size, uint32_t depth, int prettify, int coerce)
 {
     hashtable_t *visited = hash_table_new(plist_node_ptr_hash, plist_node_ptr_compare, NULL);
     if (!visited) return PLIST_ERR_NO_MEM;
-    plist_err_t err = _node_estimate_size(node, size, depth, prettify, visited);
+    plist_err_t err = _node_estimate_size(node, size, depth, prettify, coerce, visited);
     hash_table_destroy(visited);
     return err;
 }
 
 plist_err_t plist_to_json(plist_t plist, char **plist_json, uint32_t* length, int prettify)
+{
+    plist_write_options_t opts = prettify ? PLIST_OPT_NONE : PLIST_OPT_COMPACT;
+    return plist_to_json_with_options(plist, plist_json, length, opts);
+}
+
+plist_err_t plist_to_json_with_options(plist_t plist, char **plist_json, uint32_t* length, plist_write_options_t options)
 {
     uint64_t size = 0;
     plist_err_t res;
@@ -440,7 +512,10 @@ plist_err_t plist_to_json(plist_t plist, char **plist_json, uint32_t* length, in
         return PLIST_ERR_FORMAT;
     }
 
-    res = node_estimate_size((node_t)plist, &size, 0, prettify);
+    int prettify = !(options & PLIST_OPT_COMPACT);
+    int coerce = options & PLIST_OPT_COERCE;
+
+    res = node_estimate_size((node_t)plist, &size, 0, prettify, coerce);
     if (res < 0) {
         return res;
     }
@@ -451,7 +526,7 @@ plist_err_t plist_to_json(plist_t plist, char **plist_json, uint32_t* length, in
         return PLIST_ERR_NO_MEM;
     }
 
-    res = node_to_json((node_t)plist, &outbuf, 0, prettify);
+    res = node_to_json((node_t)plist, &outbuf, 0, prettify, coerce);
     if (res < 0) {
         str_buf_free(outbuf);
         *plist_json = NULL;

src/plist.c

@@ -2404,7 +2404,7 @@ plist_err_t plist_write_to_string(plist_t plist, char **output, uint32_t* length
             err = plist_to_xml(plist, output, length);
             break;
         case PLIST_FORMAT_JSON:
-            err = plist_to_json(plist, output, length, ((options & PLIST_OPT_COMPACT) == 0));
+            err = plist_to_json_with_options(plist, output, length, options);
             break;
         case PLIST_FORMAT_OSTEP:
             err = plist_to_openstep(plist, output, length, ((options & PLIST_OPT_COMPACT) == 0));
@@ -2442,7 +2442,7 @@ plist_err_t plist_write_to_stream(plist_t plist, FILE *stream, plist_format_t fo
             err = plist_to_xml(plist, &output, &length);
             break;
         case PLIST_FORMAT_JSON:
-            err = plist_to_json(plist, &output, &length, ((options & PLIST_OPT_COMPACT) == 0));
+            err = plist_to_json_with_options(plist, &output, &length, options);
             break;
         case PLIST_FORMAT_OSTEP:
             err = plist_to_openstep(plist, &output, &length, ((options & PLIST_OPT_COMPACT) == 0));

tools/Makefile.am

@@ -11,4 +11,10 @@ bin_PROGRAMS = plistutil
 plistutil_SOURCES = plistutil.c
 plistutil_LDADD = $(top_builddir)/src/libplist-2.0.la
 
+install-exec-hook:
+	cd $(DESTDIR)$(bindir) && ln -sf plistutil plist2json
+
+uninstall-hook:
+	rm -f $(DESTDIR)$(bindir)/plist2json
+
 endif

tools/plistutil.c

@@ -52,6 +52,7 @@ typedef struct _options
 #define OPT_DEBUG   (1 << 0)
 #define OPT_COMPACT (1 << 1)
 #define OPT_SORT    (1 << 2)
+#define OPT_COERCE  (1 << 3)
 
 static void print_usage(int argc, char *argv[])
 {
@@ -74,6 +75,10 @@ static void print_usage(int argc, char *argv[])
     printf("  -n, --nodepath PATH  Restrict output to nodepath defined by PATH.\n");
     printf("  -c, --compact        JSON and OpenStep only: Print output in compact form.\n");
     printf("                       By default, the output will be pretty-printed.\n");
+    printf("  -C, --coerce         JSON only: Coerce non-JSON plist types to JSON-compatible\n");
+    printf("                       representations. Date values become ISO 8601 strings,\n");
+    printf("                       data values become Base64-encoded strings, and UID values\n");
+    printf("                       become integers. Implied when invoked as plist2json.\n");
     printf("  -s, --sort           Sort all dictionary nodes lexicographically by key\n");
     printf("                       before converting to the output format.\n");
     printf("  -d, --debug          Enable extended debug output\n");
@@ -96,6 +101,7 @@ static options_t *parse_arguments(int argc, char *argv[])
         { "outfile",  required_argument, 0, 'o' },
         { "format",   required_argument, 0, 'f' },
         { "compact",  no_argument,       0, 'c' },
+        { "coerce",   no_argument,       0, 'C' },
         { "sort",     no_argument,       0, 's' },
         { "print",    required_argument, 0, 'p' },
         { "nodepath", required_argument, 0, 'n' },
@@ -106,7 +112,7 @@ static options_t *parse_arguments(int argc, char *argv[])
     };
 
     int c;
-    while ((c = getopt_long(argc, argv, "i:o:f:csp:n:dhv", long_options, NULL)) != -1)
+    while ((c = getopt_long(argc, argv, "i:o:f:cCsp:n:dhv", long_options, NULL)) != -1)
     {
         switch (c)
         {
@@ -154,6 +160,10 @@ static options_t *parse_arguments(int argc, char *argv[])
                 options->flags |= OPT_COMPACT;
                 break;
 
+            case 'C':
+                options->flags |= OPT_COERCE;
+                break;
+
             case 's':
                 options->flags |= OPT_SORT;
                 break;
@@ -230,6 +240,18 @@ int main(int argc, char *argv[])
         return 0;
     }
 
+    // detect invocation as plist2json symlink
+    {
+        char *progname = strrchr(argv[0], '/');
+        progname = progname ? progname + 1 : argv[0];
+        if (!strcmp(progname, "plist2json")) {
+            if (options->out_fmt == 0) {
+                options->out_fmt = PLIST_FORMAT_JSON;
+            }
+            options->flags |= OPT_COERCE;
+        }
+    }
+
     if (options->flags & OPT_DEBUG)
     {
         plist_set_debug(1);
@@ -404,7 +426,10 @@ int main(int argc, char *argv[])
             } else if (options->out_fmt == PLIST_FORMAT_XML) {
                 output_res = plist_to_xml(root_node, &plist_out, &size);
             } else if (options->out_fmt == PLIST_FORMAT_JSON) {
-                output_res = plist_to_json(root_node, &plist_out, &size, !(options->flags & OPT_COMPACT));
+                plist_write_options_t wropts = PLIST_OPT_NONE;
+                if (options->flags & OPT_COMPACT) wropts |= PLIST_OPT_COMPACT;
+                if (options->flags & OPT_COERCE) wropts |= PLIST_OPT_COERCE;
+                output_res = plist_to_json_with_options(root_node, &plist_out, &size, wropts);
             } else if (options->out_fmt == PLIST_FORMAT_OSTEP) {
                 output_res = plist_to_openstep(root_node, &plist_out, &size, !(options->flags & OPT_COMPACT));
             } else {