c - g_string_truncate () 上的段错误？

Question

在 C 中尝试以下操作时:

g_string_printf(qbuf,"INSERT INTO inbox (number, smsdate, text) VALUES ('%s','%04d-%02d-%02d %02d:%02d:%02d', '%s')",
          xmx.remote.number,
          xmx.smsc_time.year,
          xmx.smsc_time.month,
          xmx.smsc_time.day,
          xmx.smsc_time.hour,
          xmx.smsc_time.minute,
          xmx.smsc_time.second,
          xmx.user_data[0].u.text);

我看到以下崩溃:

Program received signal SIGSEGV, Segmentation fault.
0x00984809 in g_string_truncate () from /lib/libglib-2.0.so.0
(gdb) 

为什么会这样？调用 g_string_printf() 之前有没有初始化？

从第 2 帧开始:

(gdb) frame 2
#2  0x08049ba8 in fetching_phone (unit=0x807cd80) at main.c:152
152           g_string_printf(qbuf,"INSERT INTO inbox (number, smsdate, text) VALUES ('%s','%04d-%02d-%02d %02d:%02d:%02d', '%s')",
(gdb) ptype xmx.remote.number
type = char [40]
(gdb) ptype xmx.smsc_time.year
type = int
(gdb) ptype xmx.smsc_time.month
type = int
(gdb) ptype xmx.smsc_time.day
type = int
(gdb) ptype xmx.smsc_time.hour
type = int
(gdb) ptype xmx.smsc_time.minute
type = int
(gdb) ptype xmx.smsc_time.second
type = int
(gdb) ptype xmx.user_data[0].u.text
type = unsigned char [1601]
(gdb) 

但是，我还是找不到问题出在哪里。

Answer 1

您可能对“%s”字段有错误的指针。当您运行 gdb 时，您可以执行以下操作:

(gdb) bt
...trace...
# see the frame # of your call to g_string_printf()
(gdb) frame 5 # considering it was 5
(gdb) print xmx.remote.number
(gdb) print xmx.user_data[0].u.text
(gdb) print *xmx.remote.number
(gdb) print *xmx.user_data[0].u.text

或者您也可以检查类型(xmx.remote.number 是指针吗？)

(gdb) ptype xmx.remote.number