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068051e378
This change is trying to make two failure modes a bit easier to deep dive: 1. If a serverPanic or serverAssert occurs during the info (or module) printing, it will recursively panic, which is a lot of fun as it will just keep recursively printing. It will eventually stack overflow, but will generate a lot of text in the process. 2. When a segfault happens during the segfault handler, no information is communicated other than it happened. This can be problematic because `info` may help diagnose the real issue, but without fixing the recursive crash it might be hard to get at that info.
40 lines
1.4 KiB
C
40 lines
1.4 KiB
C
#include "redismodule.h"
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#include <strings.h>
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#include <sys/mman.h>
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#define UNUSED(V) ((void) V)
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void assertCrash(RedisModuleInfoCtx *ctx, int for_crash_report) {
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UNUSED(ctx);
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UNUSED(for_crash_report);
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RedisModule_Assert(0);
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}
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void segfaultCrash(RedisModuleInfoCtx *ctx, int for_crash_report) {
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UNUSED(ctx);
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UNUSED(for_crash_report);
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/* Compiler gives warnings about writing to a random address
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* e.g "*((char*)-1) = 'x';". As a workaround, we map a read-only area
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* and try to write there to trigger segmentation fault. */
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char *p = mmap(NULL, 4096, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
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*p = 'x';
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}
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int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
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REDISMODULE_NOT_USED(argv);
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REDISMODULE_NOT_USED(argc);
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if (RedisModule_Init(ctx,"infocrash",1,REDISMODULE_APIVER_1)
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== REDISMODULE_ERR) return REDISMODULE_ERR;
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RedisModule_Assert(argc == 1);
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if (!strcasecmp(RedisModule_StringPtrLen(argv[0], NULL), "segfault")) {
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if (RedisModule_RegisterInfoFunc(ctx, segfaultCrash) == REDISMODULE_ERR) return REDISMODULE_ERR;
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} else if(!strcasecmp(RedisModule_StringPtrLen(argv[0], NULL), "assert")) {
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if (RedisModule_RegisterInfoFunc(ctx, assertCrash) == REDISMODULE_ERR) return REDISMODULE_ERR;
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} else {
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return REDISMODULE_ERR;
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}
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return REDISMODULE_OK;
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}
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