Return errors instead of panicing

loadavg.go

@@ -25,23 +25,24 @@ type ProcLoadavg struct {
 	LastPid uint
 }
 
-func NewProcLoadavg() ProcLoadavg {
+func NewProcLoadavg() (ProcLoadavg, error) {
+	p := ProcLoadavg{}
+
 	b, err := ioutil.ReadFile("/proc/loadavg")
 	if err != nil {
-		panic(err)
+		return p, err
 	}
 
-	p := ProcLoadavg{}
-
 	parsed, err := fmt.Sscanf(string(b), "%f %f %f %d/%d %d",
 		&p.Avg1Min, &p.Avg5Min, &p.Avg15Min, &p.RunnableEntities,
 		&p.TotalEntities, &p.LastPid)
 	if parsed < 6 {
-		fmt.Println("Managed to parse only", parsed, "fields out of 6")
+		err := fmt.Errorf("Managed to parse only %d fields out of 6", parsed)
+		return p, err
 	}
 	if err != nil {
-		panic(err)
+		return p, err
 	}
 
-	return p
+	return p, nil
 }

pid_stat.go

@@ -210,15 +210,15 @@ type ProcPidStat struct {
 	CguestTime int32
 }
 
-func NewProcPidStat(pid int) ProcPidStat {
+func NewProcPidStat(pid int) (ProcPidStat, error) {
+	p := ProcPidStat{}
+
 	file := fmt.Sprintf("/proc/%d/stat", pid)
 	b, err := ioutil.ReadFile(file)
 	if err != nil {
-		panic(err)
+		return p, err
 	}
 
-	p := ProcPidStat{}
-
 	parsed, err := fmt.Sscanf(string(b),
 		"%d %s %s %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d "+
 			"%d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d",
@@ -231,11 +231,12 @@ func NewProcPidStat(pid int) ProcPidStat {
 		&p.Nswap, &p.Cnswap, &p.ExitSignal, &p.Processor, &p.RtPriority,
 		&p.Policy, &p.DelayacctBlkioTicks, &p.GuestTime, &p.CguestTime)
 	if parsed < 44 {
-		fmt.Println("Managed to parse only", parsed, "fields out of 44")
+		err := fmt.Errorf("Managed to parse only %d fields out of 44", parsed)
+		return p, err
 	}
 	if err != nil {
-		panic(err)
+		return p, err
 	}
 
-	return p
+	return p, nil
 }

pid_statm.go

@@ -17,24 +17,25 @@ type ProcPidStatm struct {
 	Dt       uint64 // Dirty pages (unused in Linux 2.6)
 }
 
-func NewProcPidStatm(pid int) ProcPidStatm {
+func NewProcPidStatm(pid int) (ProcPidStatm, error) {
+	p := ProcPidStatm{}
+
 	file := fmt.Sprintf("/proc/%d/statm", pid)
 	b, err := ioutil.ReadFile(file)
 	if err != nil {
-		panic(err)
+		return p, err
 	}
 
-	p := ProcPidStatm{}
-
 	parsed, err := fmt.Sscanf(string(b), "%d %d %d %d %d %d %d",
 		&p.Size, &p.Resident, &p.Share, &p.Text, &p.Lib, &p.Data, &p.Dt)
 
 	if parsed < 7 {
-		fmt.Println("Managed to parse only", parsed, "fields out of 7")
+		err := fmt.Errorf("Managed to parse only %d fields out of 7", parsed)
+		return p, err
 	}
 	if err != nil {
-		panic(err)
+		return p, err
 	}
 
-	return p
+	return p, nil
 }

stat.go

@@ -29,24 +29,25 @@ type ProcStat struct {
 	}
 }
 
-func NewProcStat() ProcStat {
+func NewProcStat() (ProcStat, error) {
+	p := ProcStat{}
+
 	b, err := ioutil.ReadFile("/proc/stat")
 	if err != nil {
-		panic(err)
+		return p, err
 	}
 
-	p := ProcStat{}
-
 	parsed, err := fmt.Sscanf(string(b), "cpu  %d %d %d %d %d %d %d %d %d %d",
 		&p.Cpu.User, &p.Cpu.Nice, &p.Cpu.System, &p.Cpu.Idle, &p.Cpu.Iowait,
 		&p.Cpu.Irq, &p.Cpu.Softirq, &p.Cpu.Steal, &p.Cpu.Guest,
 		&p.Cpu.GuestNice)
 	if parsed < 10 {
-		fmt.Println("Managed to parse only", parsed, "fields out of 10")
+		err := fmt.Errorf("Managed to parse only %d fields out of 10", parsed)
+		return p, err
 	}
 	if err != nil {
-		panic(err)
+		return p, err
 	}
 
-	return p
+	return p, nil
 }

uptime.go

@@ -12,21 +12,22 @@ type ProcUptime struct {
 	Idle   float64 // Time spent in idle process in seconds
 }
 
-func NewProcUptime() ProcUptime {
+func NewProcUptime() (ProcUptime, error) {
+	p := ProcUptime{}
+
 	b, err := ioutil.ReadFile("/proc/uptime")
 	if err != nil {
-		panic(err)
+		return p, err
 	}
 
-	p := ProcUptime{}
-
 	parsed, err := fmt.Sscanf(string(b), "%f %f", &p.Uptime, &p.Idle)
 	if parsed < 2 {
-		fmt.Println("Managed to parse only", parsed, "fields out of 2")
+		err := fmt.Errorf("Managed to parse only %d fields out of 2", parsed)
+		return p, err
 	}
 	if err != nil {
-		panic(err)
+		return p, err
 	}
 
-	return p
+	return p, nil
 }