From 9c4aeda96220b3f0d097d153bedd328f71f382bf Mon Sep 17 00:00:00 2001 From: Christian Beier Date: Thu, 18 Jan 2018 21:21:09 +0100 Subject: [PATCH] jshn: add functionality to read big JSON The existing read functionality feeds the complete JSON to jshn as a cmdline argument, leading to `-ash: jshn: Argument list too long` errors for JSONs bigger than ca. 100KB. This commit adds the ability to read the JSON directly from a file if wanted, removing this shell-imposed size limit. Tested on x86-64 and ar71xx. An mmap()-based solution was also evaluated, but found to make no performance difference on either platform. Signed-off-by: Christian Beier --- jshn.c | 35 +++++++++++++++++++++++++++++++++-- sh/jshn.sh | 4 ++++ 2 files changed, 37 insertions(+), 2 deletions(-) diff --git a/jshn.c b/jshn.c index 3188af5..7f67746 100644 --- a/jshn.c +++ b/jshn.c @@ -25,6 +25,8 @@ #include #include #include +#include +#include #include "list.h" #include "avl.h" @@ -305,7 +307,7 @@ out: static int usage(const char *progname) { - fprintf(stderr, "Usage: %s [-n] [-i] -r |-w\n", progname); + fprintf(stderr, "Usage: %s [-n] [-i] -r |-R |-w\n", progname); return 2; } @@ -338,6 +340,10 @@ int main(int argc, char **argv) struct env_var *vars; int i; int ch; + int fd; + struct stat sb; + char *fbuf; + int ret; avl_init(&env_vars, avl_strcmp_var, false, NULL); for (i = 0; environ[i]; i++); @@ -359,7 +365,7 @@ int main(int argc, char **argv) avl_insert(&env_vars, &vars[i].avl); } - while ((ch = getopt(argc, argv, "p:nir:w")) != -1) { + while ((ch = getopt(argc, argv, "p:nir:R:w")) != -1) { switch(ch) { case 'p': var_prefix = optarg; @@ -367,6 +373,31 @@ int main(int argc, char **argv) break; case 'r': return jshn_parse(optarg); + case 'R': + if ((fd = open(optarg, O_RDONLY)) == -1) { + fprintf(stderr, "Error opening %s\n", optarg); + return 3; + } + if (fstat(fd, &sb) == -1) { + fprintf(stderr, "Error getting size of %s\n", optarg); + close(fd); + return 3; + } + if (!(fbuf = malloc(sb.st_size))) { + fprintf(stderr, "Error allocating memory for %s\n", optarg); + close(fd); + return 3; + } + if (read(fd, fbuf, sb.st_size) != sb.st_size) { + fprintf(stderr, "Error reading %s\n", optarg); + free(fbuf); + close(fd); + return 3; + } + ret = jshn_parse(fbuf); + free(fbuf); + close(fd); + return ret; case 'w': return jshn_format(no_newline, indent); case 'n': diff --git a/sh/jshn.sh b/sh/jshn.sh index 1090814..66baccb 100644 --- a/sh/jshn.sh +++ b/sh/jshn.sh @@ -180,6 +180,10 @@ json_load() { eval "`jshn -r "$1"`" } +json_load_file() { + eval "`jshn -R "$1"`" +} + json_dump() { jshn "$@" ${JSON_PREFIX:+-p "$JSON_PREFIX"} -w } -- 2.25.1