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AP_BattMonitor: zero-terminate strings in caller rather than read_block

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It was noted that we did not increment the return value bufflen when
adding zero.  This is an ambiguity in the function declaration; if we
are told to add a zero should the return value be like strnlen (does not
include terminating null character) or read (includes all bytes used in
return buffer).

This PR makes it a non-issue by ensuring string null termination in the
caller and removing the append_zero parameter.
This commit is contained in:
Peter Barker 2022-05-02 11:03:44 +10:00 committed by Peter Barker
parent 6d7086a8ad
commit 2c0f52a8b7
2 changed files with 4 additions and 9 deletions
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11
libraries/AP_BattMonitor/AP_BattMonitor_SMBus_Generic.cpp
View File

@ -130,7 +130,7 @@ void AP_BattMonitor_SMBus_Generic::timer()
}
// read_block - returns number of characters read if successful, zero if unsuccessful
uint8_t AP_BattMonitor_SMBus_Generic::read_block(uint8_t reg, uint8_t* data, bool append_zero) const
uint8_t AP_BattMonitor_SMBus_Generic::read_block(uint8_t reg, uint8_t* data) const
{
// get length
uint8_t bufflen;
@ -164,11 +164,6 @@ uint8_t AP_BattMonitor_SMBus_Generic::read_block(uint8_t reg, uint8_t* data, boo
// copy data (excluding PEC)
memcpy(data, &buff[1], bufflen);
// optionally add zero to end
if (append_zero) {
data[bufflen] = '\0';
}
// return success
return bufflen;
}
@ -199,8 +194,8 @@ bool AP_BattMonitor_SMBus_Generic::check_pec_support()
}
// check manufacturer name
uint8_t buff[SMBUS_READ_BLOCK_MAXIMUM_TRANSFER + 1];
if (read_block(BATTMONITOR_SMBUS_MANUFACTURE_NAME, buff, true)) {
uint8_t buff[SMBUS_READ_BLOCK_MAXIMUM_TRANSFER + 1] {};
if (read_block(BATTMONITOR_SMBUS_MANUFACTURE_NAME, buff)) {
// Hitachi maxell batteries do not support PEC
if (strcmp((char*)buff, "Hitachi maxell") == 0) {
_pec_supported = false;

2
libraries/AP_BattMonitor/AP_BattMonitor_SMBus_Generic.h
View File

@ -26,7 +26,7 @@ private:
bool check_pec_support();
// read_block - returns number of characters read if successful, zero if unsuccessful
uint8_t read_block(uint8_t reg, uint8_t* data, bool append_zero) const;
uint8_t read_block(uint8_t reg, uint8_t* data) const;
uint8_t _pec_confirmed; // count of the number of times PEC has been confirmed as working
uint32_t _last_cell_update_us[BATTMONITOR_SMBUS_NUM_CELLS_MAX]; // system time of last successful read of cell voltage