根据trace到原始的source code部分 proc/fs/generic.c 作者写到的使用说明： /* * How to be a proc read function * ------------------------------ * Prototype: * int f(char *buffer, char **start, off_t offset, * int count, int *peof, void *dat) * * Assume that the buffer is "count" bytes in size. * * If you know you have supplied all the data you * have, set *peof. * * You have three ways to return data: * 0) Leave *start = NULL. (This is the default.) * Put the data of the requested offset at that * offset within the buffer. Return the number (n) * of bytes there are from the beginning of the * buffer up to the last byte of data. If the * number of supplied bytes (= n - offset) is * greater than zero and you didn't signal eof * and the reader is prepared to take more data * you will be called again with the requested * offset advanced by the number of bytes * absorbed. This interface is useful for files * no larger than the buffer. 这种方法意思是指将要读出的资料放在第一个参数栏buffer， 而将第二个参数(自订buffer空间)设为NULL。不过因为buffer 参数的空间大小为PAGE_SIZE，亦即4096KB，所以若我超过此数 值并不适用。 * 1) Set *start = an unsigned long value less than * the buffer address but greater than zero. * Put the data of the requested offset at the * beginning of the buffer. Return the number of * bytes of data placed there. If this number is * greater than zero and you didn't signal eof * and the reader is prepared to take more data * you will be called again with the requested * offset advanced by *start. This interface is * useful when you have a large file consisting * of a series of blocks which you want to count * and return as wholes. * (Hack by [email protected]) 这个方式我就不太明白了，*start通常放的是我的自订buffer 位置，此部分所指的unsigned long value less than the buffer address意思是？ 不知是否有使用过的前辈举个例子说明，感谢。 * 2) Set *start = an address within the buffer. * Put the data of the requested offset at *start. * Return the number of bytes of data placed there. * If this number is greater than zero and you * didn't signal eof and the reader is prepared to * take more data you will be called again with the * requested offset advanced by the number of bytes * absorbed. */ ※ 引述《supermin (　)》之铭言： : 我使用kernel-2.6.17，撰写kernel modules来记录一些系统资讯， : 使用与user space沟通的机制是/proc，在开完档案之後指定read function大致如下： : int procfile_read(char *buffer, char **buffer_location, : off_t offset, int buffer_length, int *eof, void *data) : { : if (offset > 0) { : ret = 0; : } else { : *buffer_location = my_buffer; : } : bufferLength = 0; : return bufferLength; : } : 其中my_buffer以及bufferLength为全域变数， : 我想在记录完一堆东西之後使用cat /proc/myfile来看我记录的东西 : 不过由於bufferLength颇大，超过10000bytes，而cat的结果被切掉了， : 只能显示部分内容，显然应该是buffer overflow的问题， : 这时候该怎麽解决才能看到全部内容呢？ --

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